It depends on how much you use of the other ingredients. The Wikibooks Cookbook says:

• � pound Flour
• � pound Butter
• � pound Eggs (4 eggs)
• � pound Sugar
• � pound assorted dried fruit (Currants, Sultanas, and Raisins, with perhaps a lesser quantity of Glac� cherries).

The traditional recipe doubled the quantities above, and eliminated the fruit. The name comes from the fact that it used a pound each of sugar, flour, butter and eggs. Happy baking.

The Pan Galactic Gargle Blaster was invented by Zaphod Beeblebrox, a major character in Douglas Adams' novel The Hitchhiker's Guide to the Galaxy. The Pan Galactic Gargle Blaster has also been described in the novel as the alcoholic equivalent to a mugging; expensive and bad for the head. Its original, fictional recipe, is as follows:

1. Take the juice from one bottle of that Ol' Janx Spirit.
2. Pour into it one measure of water from the seas of Santraginus V.
3. Allow three cubes of Arcturan Mega-gin to melt into the mixture (it must be properly iced or the benzene is lost).
4. Allow four litres of Fallian marsh gas to bubble through it.
5. Over the back of a silver spoon float a measure of Qalactin Hypermint extract.
6. Drop in the tooth of an Algolian Suntiger.
7. Sprinkle Zamphuor.
8. Add an olive.
9. Drink . . . but . . . very carefully . . .

Recipe published in Mostly Harmless

Because of the popularity of the Hitchhiker's Guideseries, several recipes exist for "Earth versions" of the Pan Galactic Gargle Blaster. The following is but one version, published in "Mostly Harmless", the newsletter of ZZ9 Plural Z Alpha, the official Hitchhiker's Guide appreciation society.

To make a Pan Galactic Gargle Blaster using Terran ingredients:Take the liquid contained in a 200 ml (6.75 oz) bottle of EverClear to remind you that your head will be clear forever if you drink too many Pan Galactic Gargle Blasters, and that your brain will clear of anything soon after you start drinking some, if not before.Into it, slowly pour a 750 ml (25 oz) bottle of Bombay Sapphire to remind you of the marvelous beauty of the old Santraginean seas, or an equal amount of Jeremiah Weed in acknowledgement of what has happened to the Santraginean Seas and their lifeforms.Now add 750 ml (25 oz) of Cold Wild Turkey, letting it run into the mixture as we run through life to remind us of all the lifeforms we meet and experience while hitchhiking through the galaxy.Speedily stirring, add 375 ml (12.7 oz) of Herradura Tequila, mixing it in to commemorate the galactic hitchhikers who died of pleasure among the vapors and gasses in the marshes of Fallia.Over the bowl of a silver spoon, let flow 1 litre (34 oz) of rum in memory of the waterfalls and their glorious rainbows encountered on your journeys through the galaxy of life.Next, drop in the worm found in a bottle of Musquil, watching it dissolve into the mixture. If the bottom falls out and the worm survives, drink at your own risk.Finally, sprinkle into the mixture some Gatorade to commemorate the lifeforms which have vanished and are becoming extinct, both sentient and non-sentient, especially those most in need of aid.

If this many Pan Galactic Gargle Blasters are too many for the number of people you think you are, mix together the following amounts of ingredients as described above for a single serving.

Recipe from Project Galactic Guide

Another recipe posted online calls for:

• 1 oz. (30 ml) EverClear
• 4 oz. (120 ml) Bombay Sapphire or Jeremiah Weed
• 4 oz. (120 ml) Cold Wild Turkey
• 2 oz. (60 ml) Herradura Tequila
• 5 oz. (150 ml) Rum
• 1 worm from bottle of Mezcal
• 2 oz. (60 ml.) Gatorade

This makes one approximately 18 ounce (0,5 l) Pan Galactic Gargle Blaster. The reason this drink seems so large is that Zaphod Beeblebrox has two heads, so when he created it, it came out to 9 ounces (2,5 dl) per head, so both were happy.

Before drinking, eat one olive to create a sweetness in it which is not there. Drink extremely carefully at your own risk, and remember where your towel is (if you can).

Recipe from Drinksmixer

Yet another recipe, found online: Ingredients:

• 35 ml Tia Maria® coffee liqueur
• 35 ml vodka
• 17.5 ml cherry brandy
• 1 dash lime juice
• 7-Up® soda
• dry cider

Method Pour the Tia maria, vodka and cherry brandy together into a pint glass. Add a dash of lime juice. Fill with equal amounts of dry cider and 7-up, and add ice cubes. Suggested serving: beer glass.

Recipe number four

Another recipe:

• 1 1/2 shots 151 Proof Rum
• 1/4 shot Tequila
• 1/4 shot Gin
• 2/3 shot Triple Sec
• 1 shot Blue Curacao
• 1 dash Bitters
• 1 dash Grenadine

Recipe number five

• 4 parts Bacardi Citron
• 1 part Bacardi 151 (for color)
• 1 part Goldschallager
• 1 part Everclear (to cut Goldschallager)

Recipe number six

Another recipe: • 1 part Everclear (or any other strong grain alcohol such as Bourbon, Moonshine, or Vodka) • 1 part Bitter Lemon (or plain Tonic Water) • 1 part Bombay Sapphire Gin (or other gin) • 1 part Yukon Jack Perma-Frost Schnapps (or other mint schnapps, or white crème de menthe) • Enough blue food coloring to make the mixture a very light sky blue

Also needed: • Sugar cubes • Cinnamon extract • Yellow food coloring (optional) • Angostura Bitters • Olives

Mix the first five ingredients and chill (usually for 24 hours). Then, take a sugar cube and let it absorb 1 milliliter of cinnamon extract and 1 drop of yellow food coloring (optional). Place three ice cubes in a glass and pour the chilled liquid mixture over these. Drop in the sugar cube and stir to dissolve, or just let it sit (if food coloring is used, often the sugar cube is just left to sit, to create a layering effect with the color). Sprinkle the Angostura Bitters in the drink, and add an olive. Drink, but very carefully.

Alternatively, one can let the sugar cube absorb 1 milliliter of Angostura Bitters, and sprinkle ground cinnamon on the top of the drink, thus omitting the cinnamon extract.

It is often more convenient to make a large amount of the mixture ahead of time and chill for a day, rather than to constantly mix more of it. It's also best to save it for a special occasion, such as Towel Day due to the work put into making the drink.

Recipe from The Bartender's Best Friend

The Bartender's Best Friend also has a recipe for the Pan Galactic Gargle Blaster as follows:

• 1/2 ounce Vodka
• 1/2 ounce Triple Sec
• 1/2 ounce Yukon Jack liqueur
• 1/2 ounce Peach Schnapps
• 1/2 ounce Jack Daniel's Tennessee whiskey
• 1/2 ounce fresh lime juice
• 1/2 ounce cranberry juice
• Fill with lemon-lime soda

Build in an ice-filled Collins glass, filling it with the soda. Stir with a long straw.

Fan Modified Shooter Version:

• ½ ounce Vodka
• ½ ounce Triple Sec
• ½ ounce Yukon Jack liqueur
• ½ ounce peach schnapps
• ½ ounce Jack Daniel's Tennessee whiskey
• ½ ounce lime juice

Pour ingredients into a shaker 2/3 of ice. Shake well. Strain into a stem-less cocktail glass. Top with one large ice cube.

Recipe from "Spiders" Nightclub in Hull,UK

Very nice and a pint of it is served for the reasonable price of £2.80

• 25ml Vodka
• 25ml Pernod
• 25ml Galliano
• 25ml Blackcurrant
• 25ml Orange juice
• Enough cider to top up

Pour over some ice, stir and enjoy!

Recipe reverse-engineered from a stain on RJ Lanning's towel

• 1 oz vodka (that Ol' Janx Spirit)
• 1 oz Clamato (oh, those Santraginus fish)
• 1 oz ice cold gin (Arcturan Mega-gin)
• 4 oz Zipang Sparking Sake (Fallian marsh gas)
• 1 oz Creme de Menthe (Qalactin Hypermint extract)
• 1 Jalepeno (tooth of an Algolian Suntiger)
• Sprinkle with lemon zest (Zamphuor)
• add an olive

WARNING: Drinking Pan Galctic Gargle Blasters may cause serious damage to the rods and cones in the human eye, thus explaining why consumers of this beverage have often reported it to be green in color when, in fact, it is not.

NOTE: This answer was taken from wikibooks. I just thought that it would serve the people of wikianswers very very well.

curtesy of wikipedia: Nigirizushi * Nigirizushi (握り寿司, lit. hand-formed sushi). This consists of an oblong mound of sushi rice that is pressed between the palms of the hands, usually with a bit of wasabi, and a topping draped over it. Toppings are typically fish such as salmon, tuna or seafood. Certain toppings are typically bound to the rice with a thin strip of nori, most commonly tako (octopus), unagi (freshwater eel), anago (sea eel), ika (squid), and tamago (sweet egg). Nigiri is generally served in pairs. * Gunkanmaki (軍艦巻, lit. warship roll). A special type of nigiri-zushi: an oval, hand-formed clump of sushi rice that has a strip of "nori" wrapped around its perimeter to form a vessel that is filled with some soft, loose or fine-chopped ingredient that requires the confinement of nori such as roe, natto, oysters, sea urchin, corn with mayonnaise, and quail eggs.Gunkan-maki was invented at the Ginza Kyubey (Kubei) restaurant in 1931;[6][7] its invention significantly expanded the repertoire of soft toppings used in sushi. * Temarizushi (手まり寿司, lit. ball sushi). It is a ball-shaped sushi made by pressing rice and fish into a ball-shaped form by hand using a plastic wrap. They are quite easy to make and thus a good starting point for beginners.[8] Rolling maki

Makizushi rolls

Makizushi and Inarizushi in a Japanese supermarket.

* Makizushi (巻き寿司, lit. rolled sushi). A cylindrical piece, formed with the help of a bamboo mat, called a makisu(巻き簾). Makizushi is generally wrapped in nori, but can occasionally be found wrapped in a thin omelette, soy paper, cucumber, or parsley. Makizushi is usually cut into six or eight pieces, which constitutes a single roll order. Below are some common types of makizushi, but many other kinds exist. ** Futomaki (太巻き, lit. large or fat rolls). A large cylindrical piece, with nori on the outside. A typical futomaki is three or four centimeters (1.5 in) in diameter. They are often made with two or three fillings that are chosen for their complementary tastes and colors. During the Setsubun festival, it is traditional in Kansai to eat uncut futomaki in its cylindrical form. Futomaki is generally vegetarian, but may include toppings such as tiny fish eggs. ** Hosomaki (細巻き, lit. thin rolls). A small cylindrical piece, with the nori on the outside. A typical hosomaki has a diameter of about two centimeters (0.75 in). They generally contain only one filling, often tuna, cucumber, kanpyō, thinly sliced carrots, or, more recently, avocado. *** Kappamaki, (河童巻き) a kind of Hosomaki filled with cucumber, is named after the Japanese legendary water imp fond of cucumbers called the kappa. Traditionally, Kappamaki is consumed to clear the palate between eating raw fish and other kinds of food, so that the flavors of the fish are distinct from the tastes of other foods. *** Tekkamaki (鉄火巻き) is a kind of Hosomaki filled with raw tuna. Although some believe that the name "Tekka", meaning 'red hot iron', alludes to the color of the tuna flesh, it actually originated as a quick snack to eat in gambling dens called "Tekkaba (鉄火場)", much like the sandwich.[9][10] *** Negitoromaki (ねぎとろ巻) is a kind of Hosomaki filled with scallion and chopped tuna. Fatty tuna is often used in this style. *** Tsunamayomaki (ツナマヨ巻) is a kind of Hosomaki filled with canned tuna tossed with mayonnaise. * Temaki (手巻き, lit. hand rolls). A large cone-shaped piece of nori on the outside and the ingredients spilling out the wide end. A typical temaki is about ten centimeters (4 in) long, and is eaten with fingers because it is too awkward to pick it up with chopsticks. For optimal taste and texture, Temaki must be eaten quickly after being made because the nori cone soon absorbs moisture from the filling and loses its crispness and becomes somewhat difficult to bite. * Uramaki (裏巻き, lit. inside-out rolls). A medium-sized cylindrical piece, with two or more fillings. Uramakidiffers from other maki because the rice is on the outside and the nori inside. The filling is in the center surrounded by nori, then a layer of rice, and an outer coating of some other ingredients such as roe or toasted sesame seeds. It can be made with different fillings such as tuna, crab meat, avocado, mayonnaise, cucumber, carrots. * Oshizushi (押し寿司, lit. pressed sushi), pressed sushi from the Kansai Region, a favourite and specialty of Osaka. A block-shaped piece formed using a wooden mold, called an oshibako. The chef lines the bottom of the oshibako with the toppings, covers them with sushi rice, and then presses the lid of the mold down to create a compact, rectilinear block. The block is removed from the mold and then cut into bite-sized pieces. Wikibooks Cookbook has a recipe/module on Inarizushi

* Inari-zushi (稲荷寿司, stuffed sushi). A pouch of fried tofu filled with usually just sushi rice. It is named after the Shinto god Inari, who is believed to have a fondness for fried tofu. The pouch is normally fashioned as deep-fried tofu (油揚げ, abura age). Regional variations include pouches are made of a thin omelette (帛紗寿司, fukusa-zushi or 茶巾寿司, chakin-zushi) or dried gourd shavings (干瓢, kanpyō). It should not be confused with inari maki, which is a roll filled with flavored fried tofu. A very large version, sweeter than normal and often containing bits of carrot, is popular in Hawaii, where it is called "cone sushi." Chirashizushi

* Chirashizushi (ちらし寿司, lit. scattered sushi). A bowl of sushi rice with other ingredients mixed in (also refers to barazushi). It is commonly eaten in Japan because it is filling, fast and easy to make. Chirashizushi most often varies regionally because it is eaten annually as a part of the Doll Festival, celebrated only during March in Japan. Chirashizushi is sometimes interesting because the ingredients are often chef's choice. ** Edomae chirashizushi (Edo-style scattered sushi) is an uncooked ingredient that is arranged artfully on top of the sushi rice in a bowl. ** Gomokuzushi(Kansai-style sushi). Cooked or uncooked ingredients mixed in the body of rice in a bowl. * Narezushi (熟れ寿司, lit. matured sushi) is a traditional form of fermented sushi. Skinned and gutted fish are stuffed with salt, placed in a wooden barrel, doused with salt again, then weighed down with a heavy tsukemonoishi (pickling stone). As days pass, water seeps out and is removed. After six months this funazushi can be eaten, remaining edible for another six months or more. Western sushi

The increasing popularity of sushi in North America, as well as around the world, has resulted in variations of sushi typically found in the West and rarely if at all in Japan. Such creations to suit the Western palate[11] were initially fueled by the invention of the California roll. A wide variety of popular rolls has evolved since. Some examples include: * California roll consists of avocado, kani kama (imitation crab stick), and cucumber, often made uramaki (with rice on the outside, nori on the inside) * Caterpillar roll generally includes avocado, unagi, kani kama, and cucumber. * Dynamite rollincludes yellowtail (hamachi), and fillings such as bean sprouts, carrots, chili and spicy mayonnaise. (Dynamite roll and Crunchy roll are essentially reversed in some parts of Canada, especially western Canada.) * Rainbow roll is typically a California roll topped with several various sashimi. * Spider rollincludes fried soft shell crab and other fillings such as cucumber, avocado, daikon sprouts or lettuce, roe, and spicy mayonnaise. * Philadelphia roll almost always consists of smoked salmon, cream cheese, cucumber, and/or onion. * Salmon roll has grilled salmon skin with sweet sauce and cucumber. * Crunchy roll a California roll deep fried tempura-style, often topped with sweet eel sauce or chili sauce. (Dynamite roll and Crunchy roll are essentially reversed in some parts of Canada, especially western Canada.) * Seattle roll consists of cucumber, avocado, and raw or smoked salmon. Other rolls may include scallops, spicy tuna, beef or chicken or teriyaki roll, okra, vegetables, and cheese. Sushi rolls can also be made with Brown rice and black rice. These have also appeared in Japanese cuisine.

A wiki is a world wide web application that allows people to add, modify, and delete content in a collaborative way. Wikipedia is a made up word. Wiki combined with "pedia" suggests an encyclopedia that's a wiki.

Wikipedia (pronunciation ) is a free, multilingual encyclopedia project operated by the non-profit Wikimedia Foundation. Its name is a portmanteau of the words wiki (a technology for creating collaborative websites) and encyclopedia. Wikipedia's 10 million articles, about a quarter of which are in English, have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone who can access the Wikipedia website. Launched in 2001 by Jimmy Wales and Larry Sanger, it is currently the largest and most popular general reference work on the Internet.

Critics of Wikipedia target its systemic bias and inconsistencies and its policy of favoring consensus over credentials in its editorial process. Wikipedia's reliability and accuracy are also an issue. Other criticisms are centered on its susceptibility to vandalism and the addition of spurious or unverified information. Scholarly work suggests that vandalism is generally short-lived.

In addition to being an encyclopedic reference, Wikipedia has received major media attention as an online source of breaking news as it is constantly updated. When Time magazine recognized "You" as its Person of the Year 2006, praising the accelerating success of online collaboration and interaction by millions of users around the world, Wikipedia was the first particular "Web 2.0" service mentioned, followed by YouTube and MySpace.

Wikipedia began as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9, 2000, under the ownership of Bomis, Inc, a web portal company. Its main figures were Jimmy Wales, Bomis CEO, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia Open Content License, switching to the GNU Free Documentation License before Wikipedia's founding at the urging of Richard Stallman.

Larry Sanger and Jimmy Wales are the founders of Wikipedia. While Wales is credited with defining the goal of making a publicly editable encyclopedia, Sanger is usually credited with the counter-intuitive strategy of using a wiki to reach that goal. On January 10, 2001, Larry Sanger proposed on the Nupedia mailing list to create a wiki as a "feeder" project for Nupedia. Wikipedia was formally launched on January 15, 2001, as a single English-language edition at www.wikipedia.com, and announced by Sanger on the Nupedia mailing list. Wikipedia's policy of "neutral point-of-view" was codified in its initial months, and was similar to Nupedia's earlier "nonbiased" policy. Otherwise, there were relatively few rules initially and Wikipedia operated independently of Nupedia.

Wikipedia gained early contributors from Nupedia, Slashdot postings, and search engine indexing. It grew to approximately 20,000 articles, and 18 language editions, by the end of 2001. By late 2002 it had reached 26 language editions, 46 by the end of 2003, and 161 by the final days of 2004. Nupedia and Wikipedia coexisted until the former's servers went down permanently in 2003, and its text was incorporated into Wikipedia. English Wikipedia passed the 2 million-article mark on September 9, 2007, making it the largest encyclopedia ever assembled, eclipsing even the Yongle Encyclopedia (1407), which had held the record for exactly 600 years.

Citing fears of commercial advertising and lack of control in a perceived English-centric Wikipedia, users of the Spanish Wikipedia forked from Wikipedia to create the Enciclopedia Libre in February 2002. Later that year, Wales announced that Wikipedia would not display advertisements, and its website was moved to wikipedia.org. Various other projects have since forked from Wikipedia for editorial reasons. Wikinfo does not require neutral point of view and allows original research. New Wikipedia-inspired projects - such as Citizendium, Scholarpedia, Conservapedia and Google's Knol - have been started to address perceived limitations of Wikipedia, such as its policies on peer review, original research and commercial advertising.

The Wikimedia Foundation was created from Wikipedia and Nupedia on June 20, 2003. It applied to the United States Patent and Trademark Office to trademark Wikipedia on September 17, 2004. The mark was granted registration status on January 10, 2006. Trademark protection was accorded by Japan on December 16, 2004, and in the European Union on January 20, 2005. Technically a service mark, the scope of the mark is for: "Provision of information in the field of general encyclopedic knowledge via the Internet". There are plans to license the use of the Wikipedia trademark for some products, such as books or DVDs.

Unlike traditional encyclopedias such as Encyclopædia Britannica, no article in Wikipedia undergoes formal peer-review process and changes to articles are made available immediately. No article is owned by its creator or any other editor, or is vetted by any recognized authority. Except for a few vandalism-prone pages that can be edited only by administrators, every article may be edited anonymously or with a user account, while only registered users may create a new article. Consequently, Wikipedia "makes no guarantee of validity" of its content. Wikipedia also does not censor itself, and it contains materials that some people, including Wikipedia editors, may find objectionable, offensive or pornographic. For instance, in 2008, Wikipedia rejected an online petition against the inclusion of Muhammad's depictions in its English edition, citing this policy. The presence of politically sensitive materials in Wikipedia had also led China to block the access to parts of the site.

Content in Wikipedia, however, is subject to the laws (in particular copyright law) in Florida, United States, where Wikipedia servers are hosted, and several editorial policies and guidelines that are intended to reinforce the notion that Wikipedia is an encyclopedia. Each entry in Wikipedia must be about a topic that is encyclopedic and thus is worthy of inclusion. A topic is deemed encyclopedic if it is "notable in the Wikipedia jargon; i.e., if it has received significant coverage in secondary reliable sources (i.e., mainstream media or major academic journals) that are independent of the subject of the topic. Second, Wikipedia must expose knowledge that is already established and recognized. In other words, it must not present, for instance, new information or original works. A claim that is likely to be challenged requires a reference to reliable sources. Within the Wikipedia community, this is often phrased as "verifiability, not truth" to express the idea that the readers are left themselves to check the truthfulness of what appears in the articles and to make their own interpretations. Finally, Wikipedia does not take a side. All opinions and viewpoints, if attributable to external sources, must enjoy appropriate share of coverage within an article. Wikipedia editors as a community write and revise those policies and guidelines and enforce them by deleting, annotating with tags or modifying article materials failing to meet them. (See also Deletionism and inclusionism)

Contributors, registered or not, can take advantage of features available in the software that empowers Wikipedia. The "History" page attached to each article contains every single past revision of the article, though a revision with libelous content, criminal threats or copyright infringements may be removed afterwards. The feature makes it easy to compare old and new versions, undo changes that an editor consider undesirable, or restore lost content. The "Discussion" pages associated with each article are used to coordinate work among multiple editors. Regular contributors often maintain a "watchlist" of articles of interest to them, so that they can easily keep tabs on all recent changes to those articles. Computer programs called bots have been used widely to remove vandalism as soon as it was made, or start articles such as geography entries in a standard format from statistical data.

The open nature of the editing model has been central to any form of criticism on Wikipedia. For example, at any point, a reader of an article cannot be certain, without consulting its "history" page, whether or not the article she is reading has been vandalized. Critics argue that non-expert editing undermines quality. Because contributors usually submit edits, rewriting small portions of an entry rather than making full-length revisions, high- and low-quality content may be intermingled within an entry. Historian Roy Rosenzweig noted: "Overall, writing is the Achilles' heel of Wikipedia. Committees rarely write well, and Wikipedia entries often have a choppy quality that results from the stringing together of sentences or paragraphs written by different people. All of these led to the question of the reliability of Wikipedia as a source of accurate information.

In 2008 two researchers proved the hypothesis that the growth of Wikipedia is sustainable.

Wikipedia has been accused of exhibiting systemic bias and inconsistency; critics argue that Wikipedia's open nature and a lack of proper sources for much of the information makes it unreliable. Some commentators suggest that Wikipedia is generally reliable, but that the reliability of any given article is not always clear. Editors of traditional reference works such as the Encyclopædia Britannica have questioned the project's utility and status as an encyclopedia. Many university lecturers discourage students from citing any encyclopedia in academic work, preferring primary sources; some specifically prohibit Wikipedia citations. Co-founder Jimmy Wales stresses that encyclopedias of any type are not usually appropriate as primary sources, and should not be relied upon as authoritative. Technology writer Bill Thompson commented that the debate was possibly "symptomatic of much learning about information which is happening in society today".

Concerns have also been raised regarding the lack of accountability that results from users' anonymity, and that it is vulnerable to vandalism, the insertion of spurious information and similar problems. In one particularly well-publicized incident, false information was introduced into the biography of American political figure John Seigenthaler, Sr. and remained undetected for four months. Some critics claim that Wikipedia's open structure makes it an easy target for Internet trolls, advertisers, and those with an agenda to push. The addition of political spin to articles by organizations including members of the U.S. House of Representatives and special interest groups has been noted, and organizations such as Microsoft have offered financial incentives to work on certain articles. These issues have been parodied, notably by Stephen Colbert in The Colbert Report.

Economist Tyler Cowen writes, "If I had to guess whether Wikipedia or the median refereed journal article on economics was more likely to be true, after a not so long think I would opt for Wikipedia." He comments that many traditional sources of non-fiction suffer from systemic biases. Novel results are over-reported in journal articles, and relevant information is omitted from news reports. But he also cautions that errors are frequently found on Internet sites, and that academics and experts must be vigilant in correcting them.

In February 2007, an article in The Harvard Crimsonnewspaper reported that some of the professors at Harvard University include Wikipedia in their syllabus, but that there is a split in their perception of using Wikipedia. In June 2007, former president of the American Library Association Michael Gorman condemned Wikipedia, along with Google, stating that academics who endorse the use of Wikipedia are "the intellectual equivalent of a dietitian who recommends a steady diet of Big Macs with everything". He also said that "a generation of intellectual sluggards incapable of moving beyond the Internet" was being produced at universities. He complains that the web-based sources are discouraging students from learning from the more rare texts which either are found only on paper or are on subscription-only web sites. In the same article Jenny Fry (a research fellow at the Oxford Internet Institute) commented on the academics who cite Wikipedia saying that: "You cannot say children are intellectually lazy because they are using the Internet when academics are using search engines in their research. The difference is that they have more experience of being critical about what is retrieved and whether it is authoritative. Children need to be told how to use the Internet in a critical and appropriate way."

There have been efforts within the Wikipedia community to improve the reliability of Wikipedia. The English-language Wikipedia has introduced an assessment scale against which the quality of articles is judged; other editions have also adopted this. Roughly 2000 articles in English have passed a rigorous set of criteria to reach the highest rank, "featured article" status; such articles are intended to provide thorough, well-written coverage of their topic, supported by many references to peer-reviewed publications. In order to improve reliability, some editors have called for "stable versions" of articles, or articles that have been reviewed by the community and locked from further editing-but the community has been unable to form a consensus in favor of such changes, partly because they would require a major software overhaul. However a similar system is being tested on the German Wikipedia, and there is an expectation that some form of that system will make its way onto the English version at some future time. Software created by Luca de Alfaro and colleagues at the University of California, Santa Cruz is now being tested that will assign "trust ratings" to individual Wikipedia contributors, with the intention that eventually only edits made by those who have established themselves as "trusted editors" will be made immediately visible.

The community has a power structure. Wikipedia's community has also been described as "cult-like, although not always with entirely negative connotations, and criticized for failing to accommodate inexperienced users. Editors in good standing in the community can run for one of many of levels of volunteer stewardship; this begins with "administrator" and goes up with "steward" and "bureaucrat". Administrators, the largest group of privileged users (for the English edition on September 30, 2008), have the ability to delete pages, lock articles from being changed in case of vandalism or editorial disputes, and block users from editing. Contrary to the name, the administrators do not enjoy any special privilege in decision-making and are prohibited from using their powers to settle content dispute. The roles of administrators, often described as "janitorial", are mostly limited to making edits that have project-wide effects and thus are disallowed to ordinary editors in order to minimize disruption, as well as banning users from making disruptive edits such as vandalism.

As Wikipedia grows with an unconventional model of encyclopedia building, "Who writes Wikipedia?" has become one of the questions frequently asked on the project, often with a reference to other Web 2.0 projects such as Digg. Jimmy Wales once argued that only "a community ... a dedicated group of a few hundred volunteers" makes the bulk of contributions to Wikipedia and that the project is therefore "much like any traditional organization". This was later disputed by Aaron Swartz, who noted that several articles he sampled had large portions of their content contributed by users with low edit counts. A 2007 study by researchers from Dartmouth College found that anonymous and infrequent contributors to Wikipedia are as reliable a source of knowledge as those contributors who register with the site. Although some contributors are authorities in their field, Wikipedia requires that even their contributions be supported by published and verifiable sources. The project's preference for consensus over credentials has been labeled "anti-elitism".

In August 2007, a website developed by computer science graduate student Virgil Griffith named WikiScanner made its public debut. WikiScanner traces the source of millions of changes made to Wikipedia by editors who are not logged in, which reveals that many of these edits come from corporations or sovereign government agencies about articles related to them, their personnel or their work, and were attempts to remove criticism.

In a 2003 study of Wikipedia as a community, economics Ph.D. student Andrea Ciffolilli argued that the low transaction costs of participating in wiki software create a catalyst for collaborative development, and that a "creative construction" approach encourages participation. In his 2008 book, The Future of the Internet and How to Stop It, Jonathan Zittrain of the Oxford Internet Institute and Harvard Law School's Berkman Center for Internet & Society cites Wikipedia's success as a case study in how open collaboration has fostered innovation on the web.

Wikipedia is hosted and funded by the Wikimedia Foundation, a non-profit organization which also operates Wikipedia-related projects such as Wikibooks. The Wikimedia chapters, local associations of Wikipedians, also participate in the promotion, the development and the funding of the project.

The operation of Wikipedia depends on MediaWiki, a custom-made, free and open source wiki software platform written in PHP and built upon the MySQL database. The software incorporates programming features such as a macro language, variables, a transclusion system for templates, and URL redirection. MediaWiki is licensed under the GNU General Public License and used by all Wikimedia projects, as well as many other wiki projects. Originally, Wikipedia ran on UseModWiki written in Perl by Clifford Adams (Phase I), which initially required CamelCase for article hyperlinks; the present double bracket style was incorporated later. Starting in January 2002 (Phase II), Wikipedia began running on a PHP wiki engine with a MySQL database; this software was custom-made for Wikipedia by Magnus Manske. The Phase II software was repeatedly modified to accommodate the exponentially increasing demand. In July 2002 (Phase III), Wikipedia shifted to the third-generation software, MediaWiki, originally written by Lee Daniel Crocker.

Wikipedia currently runs on dedicated clusters of Ubuntu servers, 300 in Florida, 26 in Amsterdam, and 23 in Yahoo!'s Korean hosting facility in Seoul. Wikipedia employed a single server until 2004, when the server setup was expanded into a distributed multitier architecture. In January 2005, the project ran on 39 dedicated servers located in Florida. This configuration included a single master database server running MySQL, multiple slave database servers, 21 web servers running the Apache HTTP Server, and seven Squid cache servers.

Wikipedia receives between 20,000 and 45,000 page requests per second, depending on time of day. Page requests are first passed to a front-end layer of Squid caching servers. Requests that cannot be served from the Squid cache are sent to load-balancing servers running the Linux Virtual Server software, which in turn pass the request to one of the Apache web servers for page rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages for anonymous users are cached in a distributed memory cache until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Two larger clusters in the Netherlands and Korea now handle much of Wikipedia's traffic load.

All text in Wikipedia is covered by GNU Free Documentation License (GFDL), a copyleft license permitting the redistribution, creation of derivative works, and commercial use of content while authors retain copyright of their work. The position that Wikipedia is merely a hosting service has been successfully used as a defense in court. Wikipedia has been working on the switch to Creative Commons licenses because the GFDL, initially designed for software manuals, is not suitable for online reference works and because the two licenses are currently incompatible.

The handling of media files (e.g., image files) varies across language editions. Some language editions, such as the English Wikipedia, include non-free image files under fair use doctrine, while the others have opted not to. This is in part because of the difference in copyright laws between countries; for example, the notion of fair use does not exist in Japanese copyright law. Media files covered by free content licenses (e.g., Creative Commons' cc-by-sa) are shared across language editions via Wikimedia Commons repository, a project operated by the Wikimedia Foundation.

There are currently 262 language editions of Wikipedia; of these, 22 have over 100,000 articles and 79 have over 1,000 articles. (See List of Wikipedias for the full list.) According to Alexa, the English subdomain (en.wikipedia.org; English Wikipedia) receives approximately 52% of Wikipedia's cumulative traffic, with the remaining split among the other languages (Spanish: 19%, French: 5%, Polish: 3%, German: 3%, Japanese: 3%, Portuguese: 2%). As of July 2008, the five largest language editions are (in order of article count) English, German, French, Polish and Japanese Wikipedias.

Since Wikipedia is web-based and therefore worldwide, contributors of a same language edition may use different dialects or may come from different countries (as is the case for the English edition). These differences may lead to some conflicts over spelling differences, (e.g. color vs. colour) or points of view. Though the various language editions are held to global policies such as "neutral point of view," they diverge on some points of policy and practice, most notably on whether images that are not licensed freely may be used under a claim of fair use. Jimmy Wales has described Wikipedia as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language". Though each language edition functions more or less independently, some efforts are made to supervise them all. They are coordinated in part by Meta, the Wikimedia Foundation's wiki devoted to maintaining all of its projects (Wikipedia and others). For instance, Meta-Wiki provides important statistics on all language editions of Wikipedia and maintain a list of articles every Wikipedia should have The list concerns basic content by subject: biography, history, geography, society, culture, science, technology, foodstuffs, and mathematics. As for the rest, it is not rare for articles strongly related to a particular language not to have counterparts in another edition. For example, articles about small towns in the United States might only be available in English.

Translated articles represent only a small portion of articles in most editions, in part because automated translation of articles is disallowed. Articles available in more than one language may offer "InterWiki" links, which link to the counterpart articles in other editions.

Several language versions have published a selection of Wikipedia articles on an optical disk version. An English version, 2006 Wikipedia CD Selection, contained about 2,000 articles. Another English version developed by Linterweb contains "1988 + articles". The Polish version contains nearly 240,000 articles. There are also a few German versions.

In addition to logistic growth in the number of its articles, Wikipedia has steadily gained status as a general reference website since its inception in 2001. According to Alexa and comScore, Wikipedia is among the ten most visited websites world-wide. Of the top ten, Wikipedia is the only non-profit website. The growth of Wikipedia has been fueled by its dominant position in Google search results; about 50% of search engine traffic to Wikipedia comes from Google, a good portion of which is related to academic research. In April 2007 the Pew Internet and American Life project found that one third of US Internet users consulted Wikipedia. In October 2006, the site was estimated to have a hypothetical market value of $580 million if it ran advertisements.

Wikipedia's content has also been used in academic studies, books, conferences, and court cases. The Parliament of Canada's website refers to Wikipedia's article on same-sex marriage in the "related links" section of its "further reading" list for the Civil Marriage Act. The encyclopedia's assertions are increasingly used as a source by organizations such as the U.S. Federal Courts and the World Intellectual Property Organization - though mainly for supporting information rather than information decisive to a case. Content appearing on Wikipedia has also been cited as a source and referenced in some U.S. intelligence agency reports.

Wikipedia has also been used as a source in journalism, sometimes without attribution, and several reporters have been dismissed for plagiarizing from Wikipedia. In July 2007, Wikipedia was the focus of a 30-minute documentary on BBC Radio 4 which argued that, with increased usage and awareness, the number of references to Wikipedia in popular culture is such that the term is one of a select band of 21st-century nouns that are so familiar (Google, Facebook, YouTube) that they no longer need explanation and are on a par with such 20th-century terms as Hoovering or Coke. Many parody Wikipedia's openness, with characters vandalizing or modifying the online encyclopedia project's articles. Notably, comedian Stephen Colbert has parodied or referenced Wikipedia on numerous episodes of his show The Colbert Report and coined the related term "wikiality".

Wikipedia has also created an impact upon forms of media. Some media sources satirize Wikipedia's susceptibility to inserted inaccuracies, such as a front-page article in The Onion in July 2006 with the title "Wikipedia Celebrates 750 Years of American Independence". Others may draw upon Wikipedia's statement that anyone can edit, such as "The Negotiation", an episode of The Office, where character Michael Scott said that "Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject, so you know you are getting the best possible information", and a select few parody Wikipedia's policies, such as the xkcd strip named "Wikipedian Protester", that also included the joke "Semi-protect the Constitution!"

The first documentary film about Wikipedia, entitled Truth in Numbers: The Wikipedia Story, is scheduled for 2009 release. Shot on several continents, the film will cover the history of Wikipedia and feature interviews with Wikipedia editors around the world. Dutch filmmaker IJsbrand van Veelen premiered his 45-minute documentary The Truth According to Wikipedia in April, 2008.

On September 16, 2007, The Washington Post reported that Wikipedia had become a focal point in the 2008 election campaign, saying, "Type a candidate's name into Google, and among the first results is a Wikipedia page, making those entries arguably as important as any ad in defining a candidate. Already, the presidential entries are being edited, dissected and debated countless times each day. An October 2007 Reuters article, entitled "Wikipedia page the latest status symbol", reported the recent phenomenon of how having a Wikipedia article vindicates one's notability.

Wikipedia won two major awards in May 2004. The first was a Golden Nica for Digital Communities of the annual Prix Ars Electronica contest; this came with a €10,000 (£6,588; $12,700) grant and an invitation to present at the PAE Cyberarts Festival in Austria later that year. The second was a Judges' Webby Award for the "community" category. Wikipedia was also nominated for a "Best Practices" Webby. On January 26, 2007, Wikipedia was also awarded the fourth highest brand ranking by the readers of brandchannel.com, receiving 15% of the votes in answer to the question "Which brand had the most impact on our lives in 2006?

In September 2008, Wikipedia received Quadriga A Mission of Enlightenment award of Werkstatt Deutschland along with Boris Tadić, Eckart Höfling and Peter Gabriel. The award was presented to Jimmy Wales by David Weinberger.

A number of interactive multimedia encyclopedias incorporating entries written by the public existed long before Wikipedia was founded. The first of these was the 1986 BBC Domesday Project, which included text (entered on BBC Micro computers) and photographs from over 1 million contributors in the UK, and covering the geography, art and culture of the UK. This was the first interactive multimedia encyclopedia (and was also the first major multimedia document connected through internal links), with the majority of articles being accessible through an interactive map of the UK. The user-interface and part of the content of the Domesday Project have now been emulated on a website. One of the most successful early online encyclopedias incorporating entries by the public was h2g2, which was also created by the BBC. The h2g2 encyclopedia was relatively light-hearted, focusing on articles which were both witty and informative. Both of these projects had similarities with Wikipedia, but neither gave full editorial freedom to public users.

Wikipedia has also spawned several sister projects. The first, "In Memoriam: September 11 Wiki", created in October 2002, detailed the September 11 attacks; this project was closed in October 2006. Wiktionary, a dictionary project, was launched in December 2002; Wikiquote, a collection of quotations, a week after Wikimedia launched, and Wikibooks, a collection of collaboratively written free books. Wikimedia has since started a number of other projects, including Wikiversity, a project for the creation of free learning materials and the provision of online learning activities.

A similar non-wiki project, the GNUPedia project, co-existed with Nupedia early in its history; however, it has been retired and its creator, free software figure Richard Stallman, has lent his support to Wikipedia.

Other websites centered on collaborative knowledge base development have drawn inspiration from or inspired Wikipedia. Some, such as Susning.nu, Enciclopedia Libre, and WikiZnanie likewise employ no formal review process, whereas others use more traditional peer review, such as Encyclopedia of Life, Stanford Encyclopedia of Philosophy, Scholarpedia, h2g2 and Everything2.

Jimmy Wales, the de facto leader of Wikipedia, said in an interview in regard to the online encyclopedia Citizendium which is overviewed by experts in their respective fields: "We welcome a diversity of efforts. If Larry's project is able to produce good work, we will benefit from it by copying it back into Wikipedia."

A wiki is a world wide web application that allows people to add, modify, and delete content in a collaborative way. Wikipedia is a made up word. Wiki combined with "pedia" suggests an encyclopedia that's a wiki.

Wikipedia (pronunciation ) is a free, multilingual encyclopedia project operated by the non-profit Wikimedia Foundation. Its name is a portmanteau of the words wiki (a technology for creating collaborative websites) and encyclopedia. Wikipedia's 10 million articles, about a quarter of which are in English, have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone who can access the Wikipedia website. Launched in 2001 by Jimmy Wales and Larry Sanger, it is currently the largest and most popular general reference work on the Internet.

Critics of Wikipedia target its systemic bias and inconsistencies and its policy of favoring consensus over credentials in its editorial process. Wikipedia's reliability and accuracy are also an issue. Other criticisms are centered on its susceptibility to vandalism and the addition of spurious or unverified information. Scholarly work suggests that vandalism is generally short-lived.

In addition to being an encyclopedic reference, Wikipedia has received major media attention as an online source of breaking news as it is constantly updated. When Time magazine recognized "You" as its Person of the Year 2006, praising the accelerating success of online collaboration and interaction by millions of users around the world, Wikipedia was the first particular "Web 2.0" service mentioned, followed by YouTube and MySpace.

Wikipedia began as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9, 2000, under the ownership of Bomis, Inc, a web portal company. Its main figures were Jimmy Wales, Bomis CEO, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia Open Content License, switching to the GNU Free Documentation License before Wikipedia's founding at the urging of Richard Stallman.

Larry Sanger and Jimmy Wales are the founders of Wikipedia. While Wales is credited with defining the goal of making a publicly editable encyclopedia, Sanger is usually credited with the counter-intuitive strategy of using a wiki to reach that goal. On January 10, 2001, Larry Sanger proposed on the Nupedia mailing list to create a wiki as a "feeder" project for Nupedia. Wikipedia was formally launched on January 15, 2001, as a single English-language edition at www.wikipedia.com, and announced by Sanger on the Nupedia mailing list. Wikipedia's policy of "neutral point-of-view" was codified in its initial months, and was similar to Nupedia's earlier "nonbiased" policy. Otherwise, there were relatively few rules initially and Wikipedia operated independently of Nupedia.

Wikipedia gained early contributors from Nupedia, Slashdot postings, and search engine indexing. It grew to approximately 20,000 articles, and 18 language editions, by the end of 2001. By late 2002 it had reached 26 language editions, 46 by the end of 2003, and 161 by the final days of 2004. Nupedia and Wikipedia coexisted until the former's servers went down permanently in 2003, and its text was incorporated into Wikipedia. English Wikipedia passed the 2 million-article mark on September 9, 2007, making it the largest encyclopedia ever assembled, eclipsing even the Yongle Encyclopedia (1407), which had held the record for exactly 600 years.

Citing fears of commercial advertising and lack of control in a perceived English-centric Wikipedia, users of the Spanish Wikipedia forked from Wikipedia to create the Enciclopedia Libre in February 2002. Later that year, Wales announced that Wikipedia would not display advertisements, and its website was moved to wikipedia.org. Various other projects have since forked from Wikipedia for editorial reasons. Wikinfo does not require neutral point of view and allows original research. New Wikipedia-inspired projects - such as Citizendium, Scholarpedia, Conservapedia and Google's Knol - have been started to address perceived limitations of Wikipedia, such as its policies on peer review, original research and commercial advertising.

The Wikimedia Foundation was created from Wikipedia and Nupedia on June 20, 2003. It applied to the United States Patent and Trademark Office to trademark Wikipedia on September 17, 2004. The mark was granted registration status on January 10, 2006. Trademark protection was accorded by Japan on December 16, 2004, and in the European Union on January 20, 2005. Technically a service mark, the scope of the mark is for: "Provision of information in the field of general encyclopedic knowledge via the Internet". There are plans to license the use of the Wikipedia trademark for some products, such as books or DVDs.

Unlike traditional encyclopedias such as Encyclopædia Britannica, no article in Wikipedia undergoes formal peer-review process and changes to articles are made available immediately. No article is owned by its creator or any other editor, or is vetted by any recognized authority. Except for a few vandalism-prone pages that can be edited only by administrators, every article may be edited anonymously or with a user account, while only registered users may create a new article. Consequently, Wikipedia "makes no guarantee of validity" of its content. Wikipedia also does not censor itself, and it contains materials that some people, including Wikipedia editors, may find objectionable, offensive or pornographic. For instance, in 2008, Wikipedia rejected an online petition against the inclusion of Muhammad's depictions in its English edition, citing this policy. The presence of politically sensitive materials in Wikipedia had also led China to block the access to parts of the site.

Content in Wikipedia, however, is subject to the laws (in particular copyright law) in Florida, United States, where Wikipedia servers are hosted, and several editorial policies and guidelines that are intended to reinforce the notion that Wikipedia is an encyclopedia. Each entry in Wikipedia must be about a topic that is encyclopedic and thus is worthy of inclusion. A topic is deemed encyclopedic if it is "notable in the Wikipedia jargon; i.e., if it has received significant coverage in secondary reliable sources (i.e., mainstream media or major academic journals) that are independent of the subject of the topic. Second, Wikipedia must expose knowledge that is already established and recognized. In other words, it must not present, for instance, new information or original works. A claim that is likely to be challenged requires a reference to reliable sources. Within the Wikipedia community, this is often phrased as "verifiability, not truth" to express the idea that the readers are left themselves to check the truthfulness of what appears in the articles and to make their own interpretations. Finally, Wikipedia does not take a side. All opinions and viewpoints, if attributable to external sources, must enjoy appropriate share of coverage within an article. Wikipedia editors as a community write and revise those policies and guidelines and enforce them by deleting, annotating with tags or modifying article materials failing to meet them. (See also Deletionism and inclusionism)

Contributors, registered or not, can take advantage of features available in the software that empowers Wikipedia. The "History" page attached to each article contains every single past revision of the article, though a revision with libelous content, criminal threats or copyright infringements may be removed afterwards. The feature makes it easy to compare old and new versions, undo changes that an editor consider undesirable, or restore lost content. The "Discussion" pages associated with each article are used to coordinate work among multiple editors. Regular contributors often maintain a "watchlist" of articles of interest to them, so that they can easily keep tabs on all recent changes to those articles. Computer programs called bots have been used widely to remove vandalism as soon as it was made, or start articles such as geography entries in a standard format from statistical data.

The open nature of the editing model has been central to any form of criticism on Wikipedia. For example, at any point, a reader of an article cannot be certain, without consulting its "history" page, whether or not the article she is reading has been vandalized. Critics argue that non-expert editing undermines quality. Because contributors usually submit edits, rewriting small portions of an entry rather than making full-length revisions, high- and low-quality content may be intermingled within an entry. Historian Roy Rosenzweig noted: "Overall, writing is the Achilles' heel of Wikipedia. Committees rarely write well, and Wikipedia entries often have a choppy quality that results from the stringing together of sentences or paragraphs written by different people. All of these led to the question of the reliability of Wikipedia as a source of accurate information.

In 2008 two researchers proved the hypothesis that the growth of Wikipedia is sustainable.

Wikipedia has been accused of exhibiting systemic bias and inconsistency; critics argue that Wikipedia's open nature and a lack of proper sources for much of the information makes it unreliable. Some commentators suggest that Wikipedia is generally reliable, but that the reliability of any given article is not always clear. Editors of traditional reference works such as the Encyclopædia Britannica have questioned the project's utility and status as an encyclopedia. Many university lecturers discourage students from citing any encyclopedia in academic work, preferring primary sources; some specifically prohibit Wikipedia citations. Co-founder Jimmy Wales stresses that encyclopedias of any type are not usually appropriate as primary sources, and should not be relied upon as authoritative. Technology writer Bill Thompson commented that the debate was possibly "symptomatic of much learning about information which is happening in society today".

Concerns have also been raised regarding the lack of accountability that results from users' anonymity, and that it is vulnerable to vandalism, the insertion of spurious information and similar problems. In one particularly well-publicized incident, false information was introduced into the biography of American political figure John Seigenthaler, Sr. and remained undetected for four months. Some critics claim that Wikipedia's open structure makes it an easy target for Internet trolls, advertisers, and those with an agenda to push. The addition of political spin to articles by organizations including members of the U.S. House of Representatives and special interest groups has been noted, and organizations such as Microsoft have offered financial incentives to work on certain articles. These issues have been parodied, notably by Stephen Colbert in The Colbert Report.

Economist Tyler Cowen writes, "If I had to guess whether Wikipedia or the median refereed journal article on economics was more likely to be true, after a not so long think I would opt for Wikipedia." He comments that many traditional sources of non-fiction suffer from systemic biases. Novel results are over-reported in journal articles, and relevant information is omitted from news reports. But he also cautions that errors are frequently found on Internet sites, and that academics and experts must be vigilant in correcting them.

In February 2007, an article in The Harvard Crimsonnewspaper reported that some of the professors at Harvard University include Wikipedia in their syllabus, but that there is a split in their perception of using Wikipedia. In June 2007, former president of the American Library Association Michael Gorman condemned Wikipedia, along with Google, stating that academics who endorse the use of Wikipedia are "the intellectual equivalent of a dietitian who recommends a steady diet of Big Macs with everything". He also said that "a generation of intellectual sluggards incapable of moving beyond the Internet" was being produced at universities. He complains that the web-based sources are discouraging students from learning from the more rare texts which either are found only on paper or are on subscription-only web sites. In the same article Jenny Fry (a research fellow at the Oxford Internet Institute) commented on the academics who cite Wikipedia saying that: "You cannot say children are intellectually lazy because they are using the Internet when academics are using search engines in their research. The difference is that they have more experience of being critical about what is retrieved and whether it is authoritative. Children need to be told how to use the Internet in a critical and appropriate way."

There have been efforts within the Wikipedia community to improve the reliability of Wikipedia. The English-language Wikipedia has introduced an assessment scale against which the quality of articles is judged; other editions have also adopted this. Roughly 2000 articles in English have passed a rigorous set of criteria to reach the highest rank, "featured article" status; such articles are intended to provide thorough, well-written coverage of their topic, supported by many references to peer-reviewed publications. In order to improve reliability, some editors have called for "stable versions" of articles, or articles that have been reviewed by the community and locked from further editing-but the community has been unable to form a consensus in favor of such changes, partly because they would require a major software overhaul. However a similar system is being tested on the German Wikipedia, and there is an expectation that some form of that system will make its way onto the English version at some future time. Software created by Luca de Alfaro and colleagues at the University of California, Santa Cruz is now being tested that will assign "trust ratings" to individual Wikipedia contributors, with the intention that eventually only edits made by those who have established themselves as "trusted editors" will be made immediately visible.

The community has a power structure. Wikipedia's community has also been described as "cult-like, although not always with entirely negative connotations, and criticized for failing to accommodate inexperienced users. Editors in good standing in the community can run for one of many of levels of volunteer stewardship; this begins with "administrator" and goes up with "steward" and "bureaucrat". Administrators, the largest group of privileged users (for the English edition on September 30, 2008), have the ability to delete pages, lock articles from being changed in case of vandalism or editorial disputes, and block users from editing. Contrary to the name, the administrators do not enjoy any special privilege in decision-making and are prohibited from using their powers to settle content dispute. The roles of administrators, often described as "janitorial", are mostly limited to making edits that have project-wide effects and thus are disallowed to ordinary editors in order to minimize disruption, as well as banning users from making disruptive edits such as vandalism.

As Wikipedia grows with an unconventional model of encyclopedia building, "Who writes Wikipedia?" has become one of the questions frequently asked on the project, often with a reference to other Web 2.0 projects such as Digg. Jimmy Wales once argued that only "a community ... a dedicated group of a few hundred volunteers" makes the bulk of contributions to Wikipedia and that the project is therefore "much like any traditional organization". This was later disputed by Aaron Swartz, who noted that several articles he sampled had large portions of their content contributed by users with low edit counts. A 2007 study by researchers from Dartmouth College found that anonymous and infrequent contributors to Wikipedia are as reliable a source of knowledge as those contributors who register with the site. Although some contributors are authorities in their field, Wikipedia requires that even their contributions be supported by published and verifiable sources. The project's preference for consensus over credentials has been labeled "anti-elitism".

In August 2007, a website developed by computer science graduate student Virgil Griffith named WikiScanner made its public debut. WikiScanner traces the source of millions of changes made to Wikipedia by editors who are not logged in, which reveals that many of these edits come from corporations or sovereign government agencies about articles related to them, their personnel or their work, and were attempts to remove criticism.

In a 2003 study of Wikipedia as a community, economics Ph.D. student Andrea Ciffolilli argued that the low transaction costs of participating in wiki software create a catalyst for collaborative development, and that a "creative construction" approach encourages participation. In his 2008 book, The Future of the Internet and How to Stop It, Jonathan Zittrain of the Oxford Internet Institute and Harvard Law School's Berkman Center for Internet & Society cites Wikipedia's success as a case study in how open collaboration has fostered innovation on the web.

Wikipedia is hosted and funded by the Wikimedia Foundation, a non-profit organization which also operates Wikipedia-related projects such as Wikibooks. The Wikimedia chapters, local associations of Wikipedians, also participate in the promotion, the development and the funding of the project.

The operation of Wikipedia depends on MediaWiki, a custom-made, free and open source wiki software platform written in PHP and built upon the MySQL database. The software incorporates programming features such as a macro language, variables, a transclusion system for templates, and URL redirection. MediaWiki is licensed under the GNU General Public License and used by all Wikimedia projects, as well as many other wiki projects. Originally, Wikipedia ran on UseModWiki written in Perl by Clifford Adams (Phase I), which initially required CamelCase for article hyperlinks; the present double bracket style was incorporated later. Starting in January 2002 (Phase II), Wikipedia began running on a PHP wiki engine with a MySQL database; this software was custom-made for Wikipedia by Magnus Manske. The Phase II software was repeatedly modified to accommodate the exponentially increasing demand. In July 2002 (Phase III), Wikipedia shifted to the third-generation software, MediaWiki, originally written by Lee Daniel Crocker.

Wikipedia currently runs on dedicated clusters of Ubuntu servers, 300 in Florida, 26 in Amsterdam, and 23 in Yahoo!'s Korean hosting facility in Seoul. Wikipedia employed a single server until 2004, when the server setup was expanded into a distributed multitier architecture. In January 2005, the project ran on 39 dedicated servers located in Florida. This configuration included a single master database server running MySQL, multiple slave database servers, 21 web servers running the Apache HTTP Server, and seven Squid cache servers.

Wikipedia receives between 20,000 and 45,000 page requests per second, depending on time of day. Page requests are first passed to a front-end layer of Squid caching servers. Requests that cannot be served from the Squid cache are sent to load-balancing servers running the Linux Virtual Server software, which in turn pass the request to one of the Apache web servers for page rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages for anonymous users are cached in a distributed memory cache until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Two larger clusters in the Netherlands and Korea now handle much of Wikipedia's traffic load.

All text in Wikipedia is covered by GNU Free Documentation License (GFDL), a copyleft license permitting the redistribution, creation of derivative works, and commercial use of content while authors retain copyright of their work. The position that Wikipedia is merely a hosting service has been successfully used as a defense in court. Wikipedia has been working on the switch to Creative Commons licenses because the GFDL, initially designed for software manuals, is not suitable for online reference works and because the two licenses are currently incompatible.

The handling of media files (e.g., image files) varies across language editions. Some language editions, such as the English Wikipedia, include non-free image files under fair use doctrine, while the others have opted not to. This is in part because of the difference in copyright laws between countries; for example, the notion of fair use does not exist in Japanese copyright law. Media files covered by free content licenses (e.g., Creative Commons' cc-by-sa) are shared across language editions via Wikimedia Commons repository, a project operated by the Wikimedia Foundation.

There are currently 262 language editions of Wikipedia; of these, 22 have over 100,000 articles and 79 have over 1,000 articles. (See List of Wikipedias for the full list.) According to Alexa, the English subdomain (en.wikipedia.org; English Wikipedia) receives approximately 52% of Wikipedia's cumulative traffic, with the remaining split among the other languages (Spanish: 19%, French: 5%, Polish: 3%, German: 3%, Japanese: 3%, Portuguese: 2%). As of July 2008, the five largest language editions are (in order of article count) English, German, French, Polish and Japanese Wikipedias.

Since Wikipedia is web-based and therefore worldwide, contributors of a same language edition may use different dialects or may come from different countries (as is the case for the English edition). These differences may lead to some conflicts over spelling differences, (e.g. color vs. colour) or points of view. Though the various language editions are held to global policies such as "neutral point of view," they diverge on some points of policy and practice, most notably on whether images that are not licensed freely may be used under a claim of fair use. Jimmy Wales has described Wikipedia as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language". Though each language edition functions more or less independently, some efforts are made to supervise them all. They are coordinated in part by Meta, the Wikimedia Foundation's wiki devoted to maintaining all of its projects (Wikipedia and others). For instance, Meta-Wiki provides important statistics on all language editions of Wikipedia and maintain a list of articles every Wikipedia should have The list concerns basic content by subject: biography, history, geography, society, culture, science, technology, foodstuffs, and mathematics. As for the rest, it is not rare for articles strongly related to a particular language not to have counterparts in another edition. For example, articles about small towns in the United States might only be available in English.

Translated articles represent only a small portion of articles in most editions, in part because automated translation of articles is disallowed. Articles available in more than one language may offer "InterWiki" links, which link to the counterpart articles in other editions.

Several language versions have published a selection of Wikipedia articles on an optical disk version. An English version, 2006 Wikipedia CD Selection, contained about 2,000 articles. Another English version developed by Linterweb contains "1988 + articles". The Polish version contains nearly 240,000 articles. There are also a few German versions.

In addition to logistic growth in the number of its articles, Wikipedia has steadily gained status as a general reference website since its inception in 2001. According to Alexa and comScore, Wikipedia is among the ten most visited websites world-wide. Of the top ten, Wikipedia is the only non-profit website. The growth of Wikipedia has been fueled by its dominant position in Google search results; about 50% of search engine traffic to Wikipedia comes from Google, a good portion of which is related to academic research. In April 2007 the Pew Internet and American Life project found that one third of US Internet users consulted Wikipedia. In October 2006, the site was estimated to have a hypothetical market value of $580 million if it ran advertisements.

Wikipedia's content has also been used in academic studies, books, conferences, and court cases. The Parliament of Canada's website refers to Wikipedia's article on same-sex marriage in the "related links" section of its "further reading" list for the Civil Marriage Act. The encyclopedia's assertions are increasingly used as a source by organizations such as the U.S. Federal Courts and the World Intellectual Property Organization - though mainly for supporting information rather than information decisive to a case. Content appearing on Wikipedia has also been cited as a source and referenced in some U.S. intelligence agency reports.

Wikipedia has also been used as a source in journalism, sometimes without attribution, and several reporters have been dismissed for plagiarizing from Wikipedia. In July 2007, Wikipedia was the focus of a 30-minute documentary on BBC Radio 4 which argued that, with increased usage and awareness, the number of references to Wikipedia in popular culture is such that the term is one of a select band of 21st-century nouns that are so familiar (Google, Facebook, YouTube) that they no longer need explanation and are on a par with such 20th-century terms as Hoovering or Coke. Many parody Wikipedia's openness, with characters vandalizing or modifying the online encyclopedia project's articles. Notably, comedian Stephen Colbert has parodied or referenced Wikipedia on numerous episodes of his show The Colbert Report and coined the related term "wikiality".

Wikipedia has also created an impact upon forms of media. Some media sources satirize Wikipedia's susceptibility to inserted inaccuracies, such as a front-page article in The Onion in July 2006 with the title "Wikipedia Celebrates 750 Years of American Independence". Others may draw upon Wikipedia's statement that anyone can edit, such as "The Negotiation", an episode of The Office, where character Michael Scott said that "Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject, so you know you are getting the best possible information", and a select few parody Wikipedia's policies, such as the xkcd strip named "Wikipedian Protester", that also included the joke "Semi-protect the Constitution!"

The first documentary film about Wikipedia, entitled Truth in Numbers: The Wikipedia Story, is scheduled for 2009 release. Shot on several continents, the film will cover the history of Wikipedia and feature interviews with Wikipedia editors around the world. Dutch filmmaker IJsbrand van Veelen premiered his 45-minute documentary The Truth According to Wikipedia in April, 2008.

On September 16, 2007, The Washington Post reported that Wikipedia had become a focal point in the 2008 election campaign, saying, "Type a candidate's name into Google, and among the first results is a Wikipedia page, making those entries arguably as important as any ad in defining a candidate. Already, the presidential entries are being edited, dissected and debated countless times each day. An October 2007 Reuters article, entitled "Wikipedia page the latest status symbol", reported the recent phenomenon of how having a Wikipedia article vindicates one's notability.

Wikipedia won two major awards in May 2004. The first was a Golden Nica for Digital Communities of the annual Prix Ars Electronica contest; this came with a €10,000 (£6,588; $12,700) grant and an invitation to present at the PAE Cyberarts Festival in Austria later that year. The second was a Judges' Webby Award for the "community" category. Wikipedia was also nominated for a "Best Practices" Webby. On January 26, 2007, Wikipedia was also awarded the fourth highest brand ranking by the readers of brandchannel.com, receiving 15% of the votes in answer to the question "Which brand had the most impact on our lives in 2006?

In September 2008, Wikipedia received Quadriga A Mission of Enlightenment award of Werkstatt Deutschland along with Boris Tadić, Eckart Höfling and Peter Gabriel. The award was presented to Jimmy Wales by David Weinberger.

A number of interactive multimedia encyclopedias incorporating entries written by the public existed long before Wikipedia was founded. The first of these was the 1986 BBC Domesday Project, which included text (entered on BBC Micro computers) and photographs from over 1 million contributors in the UK, and covering the geography, art and culture of the UK. This was the first interactive multimedia encyclopedia (and was also the first major multimedia document connected through internal links), with the majority of articles being accessible through an interactive map of the UK. The user-interface and part of the content of the Domesday Project have now been emulated on a website. One of the most successful early online encyclopedias incorporating entries by the public was h2g2, which was also created by the BBC. The h2g2 encyclopedia was relatively light-hearted, focusing on articles which were both witty and informative. Both of these projects had similarities with Wikipedia, but neither gave full editorial freedom to public users.

Wikipedia has also spawned several sister projects. The first, "In Memoriam: September 11 Wiki", created in October 2002, detailed the September 11 attacks; this project was closed in October 2006. Wiktionary, a dictionary project, was launched in December 2002; Wikiquote, a collection of quotations, a week after Wikimedia launched, and Wikibooks, a collection of collaboratively written free books. Wikimedia has since started a number of other projects, including Wikiversity, a project for the creation of free learning materials and the provision of online learning activities.

A similar non-wiki project, the GNUPedia project, co-existed with Nupedia early in its history; however, it has been retired and its creator, free software figure Richard Stallman, has lent his support to Wikipedia.

Other websites centered on collaborative knowledge base development have drawn inspiration from or inspired Wikipedia. Some, such as Susning.nu, Enciclopedia Libre, and WikiZnanie likewise employ no formal review process, whereas others use more traditional peer review, such as Encyclopedia of Life, Stanford Encyclopedia of Philosophy, Scholarpedia, h2g2 and Everything2.

Jimmy Wales, the de facto leader of Wikipedia, said in an interview in regard to the online encyclopedia Citizendium which is overviewed by experts in their respective fields: "We welcome a diversity of efforts. If Larry's project is able to produce good work, we will benefit from it by copying it back into Wikipedia."

Wikipedia is a free,[5] web-based and collaborative multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its name is a portmanteau of the words wiki (a technology for creating collaborative websites, from the Hawaiian word wiki, meaning "quick") and encyclopedia. Wikipedia's 13 million articles (3 million in English) have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone who can access the Wikipedia website.[6] Launched in 2001 by Jimmy Wales and Larry Sanger,[7] it is currently the largest and most popular general reference work on the Internet.[3][8][9][10] Critics of Wikipedia accuse it of systemic bias and inconsistencies (including undue weight given to popular culture),[11] and allege that it favors consensus over credentials in its editorial process.[12] Wikipedia's reliability and accuracy are also an issue.[13] Other criticisms center on its susceptibility to vandalism and the addition of spurious or unverified information,[14] though scholarly work suggests that vandalism is generally short-lived.[15][16] Wikipedia's departure from the expert-driven style of the encyclopedia building mode and the large presence of unacademic contents have been noted several times. When Time magazine recognized You as its Person of the Year for 2006, acknowledging the accelerating success of online collaboration and interaction by millions of users around the world, it cited Wikipedia as one of three examples of Web 2.0 services, along with YouTube and MySpace.[17] Some noted the importance of Wikipedia not only as an encyclopedic reference but also as a frequently updated news resource because of how quickly articles about recent events appear.[18][19] [hide]

* 1 History * 2 Nature of Wikipedia ** 2.1 Editing model ** 2.2 Consequence of the open editing model ** 2.3 Coverage of topics ** 2.4 Wikipedia community * 3 Operation ** 3.1 Wikimedia Foundation and the Wikimedia chapters ** 3.2 Software and hardware ** 3.3 Delivery media * 4 License and language editions * 5 Cultural significance * 6 Related projects * 7 See also * 8 Notes * 9 References * 10 External links Main article: History of Wikipedia

Wikipedia originally developed from another encyclopedia project, Nupedia.

Wikipedia began as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9, 2000, under the ownership of Bomis, Inc, a web portal company. Its main figures were Jimmy Wales, Bomis CEO, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia Open Content License, switching to the GNU Free Documentation License before Wikipedia's founding at the urging of Richard Stallman.[20] Larry Sanger and Jimmy Wales are the founders of Wikipedia.[21][22] While Wales is credited with defining the goal of making a publicly editable encyclopedia,[23][24] Sanger is usually credited with the strategy of using a wiki to reach that goal.[25] On January 10, 2001, Larry Sanger proposed on the Nupedia mailing list to create a wiki as a "feeder" project for Nupedia.[26] Wikipedia was formally launched on January 15, 2001, as a single English-language edition at www.wikipedia.com,[27] and announced by Sanger on the Nupedia mailing list.[23] Wikipedia's policy of "neutral point-of-view"[28] was codified in its initial months, and was similar to Nupedia's earlier "nonbiased" policy. Otherwise, there were relatively few rules initially and Wikipedia operated independently of Nupedia.[23] Graph of the article count for the English Wikipedia, from January 10, 2001, to September 9, 2007 (the date of the two-millionth article)

Wikipedia gained early contributors from Nupedia, Slashdot postings, and web search engine indexing. It grew to approximately 20,000 articles, and 18 language editions, by the end of 2001. By late 2002 it had reached 26 language editions, 46 by the end of 2003, and 161 by the final days of 2004.[29] Nupedia and Wikipedia coexisted until the former's servers were taken down permanently in 2003, and its text was incorporated into Wikipedia. English Wikipedia passed the 2 million-article mark on September 9, 2007, making it the largest encyclopedia ever assembled, eclipsing even the Yongle Encyclopedia (1407), which had held the record for exactly 600 years.[30] Citing fears of commercial advertising and lack of control in a perceived English-centric Wikipedia, users of the Spanish Wikipedia Forked from Wikipedia to create the Enciclopedia Libre in February 2002.[31] Later that year, Wales announced that Wikipedia would not display advertisements, and its website was moved to wikipedia.org.[32] Various other projects have since forked from Wikipedia for editorial reasons. Wikinfo does not require a neutral point of view and allows original research. New Wikipedia-inspired projects - such as Citizendium, Scholarpedia, Conservapedia, and Google's Knol[33] - have been started to address perceived limitations of Wikipedia, such as its policies on peer review, original research, and commercial advertising. Though the English Wikipedia reached 3 million articles in August 2009, the growth of the edition, in terms of the numbers of articles and of contributors, appeared to have abruptly flattened around Spring 2007.[34] In July 2007 about 2,200 articles were added daily to the encyclopedia; today that average is 1,300. A team led by Ed H Chi at the Palo Alto Research Center speculated that this is due to the increasing exclusiveness of the project. New or occasional editors have significantly higher rates of their edits reverted than an "elite" group of regular editors. This makes it difficult for the project to recruit and retain new contributors, resulting in the stagnation in article creation.

In April 2009, the Wikimedia Foundation conducted a Wikipedia usability study, questioning users about the editing mechanism.[35]

In departure from the style of traditional encyclopedias such as Encyclopædia Britannica, Wikipedia employs the open editing model called "wiki". Except for a few vandalism-prone pages that can be edited only by established users, or in extreme cases only by administrators, every article may be edited anonymously or with a user account, while only registered users may create a new article (only in English edition). No article is owned by its creator or any other editor, or is vetted by any recognized authority; rather, the articles are collectively owned by a community of editors. [36] Most importantly, when changes to an article are made, they become available immediately before undergoing any review, no matter if they contain an error, are somehow misguided or even patent nonsense. The German edition of Wikipedia is an exception to this rule: it has been testing a system of maintaining "stable versions" of articles,[37] to allow a reader to see versions of articles that have passed certain reviews. Other language editions have not reached a consensus to implement this "flagged revisions" proposal.[38][39] Another proposal is the use of software to create "trust ratings" for individual Wikipedia contributors and using those ratings to determine which changes will be made visible immediately.[40] Editors keep track of changes to articles by checking the difference between two revisions of a page, displayed here in red.

Contributors, registered or not, can take advantage of features available in the software that powers Wikipedia. The "History" page attached to each article records every single past revision of the article, though a revision with libelous content, criminal threats or copyright infringements may be removed afterwards.[41][42] This feature makes it easy to compare old and new versions, undo changes that an editor considers undesirable, or restore lost content. The "Discussion" pages associated with each article are used to coordinate work among multiple editors.[43] Regular contributors often maintain a "watchlist" of articles of interest to them, so that they can easily keep tabs on all recent changes to those articles. Computer programs called Internet bots have been used widely to remove vandalism as soon as it was made,[16] to correct common misspellings and stylistic issues, or to start articles such as geography entries in a standard format from statistical data. Articles in Wikipedia are organized roughly in three ways: according to their development statuses, their subject matters and the access levels required for edits. The most developed state of articles is called "featured article": they are precisely ones that someday get featured in the main page of Wikipedia.[44][45] Researcher Giacomo Poderi found that articles tend to reach the FA status via intensive works of few editors, and that the categories such as history, media, music and warfare have higher ratio of featured articles than those such as computing, mathematics, language & linguistics and philosophy & psychology, casting a doubt to the equation "more edits equal higher quality." In 2007, in preparation for producing a print version, the English-language Wikipedia introduced an assessment scale against which the quality of articles is judged;[46] other editions have also adopted this. In 2008, two researchers theorized that the growth of Wikipedia is sustainable.[47] : See also: Reliability of Wikipedia, Criticism of Wikipedia, Academic studies of Wikipedia. The open nature of the editing model has been central to most criticism of Wikipedia. For example, at any point, a reader of an article cannot be certain whether or not the article she is reading has been vandalized. Former Encyclopaedia Britannica editor-in-chief Robert McHenry once described this by saying:[48] The user who visits Wikipedia to learn about some subject, to confirm some matter of fact, is rather in the position of a visitor to a public restroom. It may be obviously dirty, so that he knows to exercise great care, or it may seem fairly clean, so that he may be lulled into a false sense of security. What he certainly does not know is who has used the facilities before him. and popularized the claim that Wikipedia is a "faith-based encyclopedia."[citation needed] Critics argue that non-expert editing undermines quality. Because contributors usually rewrite small portions of an entry rather than making full-length revisions, high- and low-quality content may be intermingled within an entry. Historian Roy Rosenzweig noted: "Overall, writing is the Achilles' heel of Wikipedia. Committees rarely write well, and Wikipedia entries often have a choppy quality that results from the stringing together of sentences or paragraphs written by different people."[49] All of these led to the question of the reliability of Wikipedia as a source of accurate information. John Seigenthaler has described Wikipedia as "a flawed and irresponsible research tool."[50]

As a consequence of the open structure, Wikipedia "makes no guarantee of validity" of its content, since no one is ultimately responsible for any claims appearing in it.[51] Concerns have been raised regarding the lack of accountability that results from users' anonymity,[52] the insertion of spurious information, vandalism, and similar problems. In one particularly well-publicized incident, false information was introduced into the biography of American political figure John Seigenthaler and remained undetected for four months.[50] John Seigenthaler, the founding editorial director of USA Today and founder of the Freedom Forum First Amendment Center at Vanderbilt University, called Jimmy Wales and asked him, "...Do you ...have any way to know who wrote that?" "No, we don't", said Jimmy.[53] Some critics claim that Wikipedia's open structure makes it an easy target for Internet trolls, spams, and those with an agenda to push.[41][54] The addition of political spin to articles by organizations including members of the U.S. House of Representatives and special interest groups[14] has been noted,[55] and organizations such as Microsoft have offered financial incentives to work on certain articles.[56] These issues have been parodied, notably by Stephen Colbert in The Colbert Report.[57] : See also: Notability in Wikipedia. As an encyclopedia building project, Wikipedia seeks to create a summary of all human knowledge: all of topics covered by a conventional print encyclopedia plus any other "notable" (therefore verifiable by published sources) topics, which are permitted by unlimited disk space.[58] In particular, it contains materials that some people, including Wikipedia editors,[59] may find objectionable, offensive, or pornographic.[60] It was made clear that this policy is not up for debate, and the policy has sometimes proved controversial. For instance, in 2008, Wikipedia rejected an online petition against the inclusion of Muhammad's depictions in its English edition, citing this policy. The presence of politically sensitive materials in Wikipedia had also led the People's Republic of China to block access to parts of the site.[61] (See also: IWF block of Wikipedia) Content in Wikipedia is subject to the laws (in particular copyright law) in Florida, where Wikipedia servers are hosted, and several editorial policies and guidelines that are intended to reinforce the notion that Wikipedia is an encyclopedia. Each entry in Wikipedia must be about a topic that is encyclopedic and thus is worthy of inclusion. A topic is deemed encyclopedic if it is "notable"[62] in the Wikipedia jargon; i.e., if it has received significant coverage in secondary reliable sources (i.e., mainstream media or major academic journals) that are independent of the subject of the topic. Second, Wikipedia must expose knowledge that is already established and recognized.[63] In other words, it must not present, for instance, new information or original works. A claim that is likely to be challenged requires a reference to reliable sources. Within the Wikipedia community, this is often phrased as "verifiability, not truth" to express the idea that the readers are left themselves to check the truthfulness of what appears in the articles and to make their own interpretations.[64] Finally, Wikipedia does not take a side.[65] All opinions and viewpoints, if attributable to external sources, must enjoy appropriate share of coverage within an article.[66] Wikipedia editors as a community write and revise those policies and guidelines[67] and enforce them by deleting, annotating with tags, or modifying article materials failing to meet them. (See also deletionism and inclusionism)[68][69] However, Wikipedia has been accused of exhibiting systemic bias and inconsistency;[13] critics argue that Wikipedia's open nature and a lack of proper sources for much of the information makes it unreliable.[70] Some commentators suggest that Wikipedia is generally reliable, but that the reliability of any given article is not always clear.[12] Editors of traditional reference works such as the Encyclopædia Britannica have questioned the project's utility and status as an encyclopedia.[71] Many university lecturers discourage students from citing any encyclopedia in academic work, preferring primary sources;[72] some specifically prohibit Wikipedia citations.[73] Co-founder Jimmy Wales stresses that encyclopedias of any type are not usually appropriate as primary sources, and should not be relied upon as authoritative.[74] Andrew Lih, author of the 2009 book The Wikipedia Revolution, notes: "A wiki has all its activities happening in the open for inspection... Trust is built by observing the actions of others in the community and discovering people with like or complementary interests."[75] Economist Tyler Cowen writes, "If I had to guess whether Wikipedia or the median refereed journal article on economics was more likely to be true, after a not so long think I would opt for Wikipedia." He comments that many traditional sources of non-fiction suffer from systemic biases. Novel results are over-reported in journal articles, and relevant information is omitted from news reports. However, he also cautions that errors are frequently found on Internet sites, and that academics and experts must be vigilant in correcting them.[76] In February 2007, an article in The Harvard Crimsonnewspaper reported that some of the professors at Harvard University include Wikipedia in their syllabus, but that there is a split in their perception of using Wikipedia.[77] In June 2007, former president of the American Library Association Michael Gorman condemned Wikipedia, along with Google,[78] stating that academics who endorse the use of Wikipedia are "the intellectual equivalent of a dietitian who recommends a steady diet of Big Macs with everything". He also said that "a generation of intellectual sluggards incapable of moving beyond the Internet" was being produced at universities. He complains that the web-based sources are discouraging students from learning from the more rare texts which are either found only on paper or are on subscription-only web sites. In the same article Jenny Fry (a research fellow at the Oxford Internet Institute) commented on academics who cite Wikipedia, saying that: "You cannot say children are intellectually lazy because they are using the Internet when academics are using search engines in their research. The difference is that they have more experience of being critical about what is retrieved and whether it is authoritative. Children need to be told how to use the Internet in a critical and appropriate way."[78] The Wikipedia community has established "a bureaucracy of sorts", including "a clear power structure that gives volunteer administrators the authority to exercise editorial control."[79][80][81] Wikipedia's community has also been described as "cult-like",[82] although not always with entirely negative connotations,[83] and criticized for failing to accommodate inexperienced users.[84] Editors in good standing in the community can run for one of many levels of volunteer stewardship; this begins with "administrator",[85][86] a group of privileged users who have the ability to delete pages, lock articles from being changed in case of vandalism or editorial disputes, and block users from editing. Despite the name, administrators do not enjoy any special privilege in decision-making; instead they are mostly limited to making edits that have project-wide effects and thus are disallowed to ordinary editors, and to ban users making disruptive edits (such as vandalism).[87] Wikimania, an annual conference for users of Wikipedia and other projects operated by the Wikimedia Foundation.

As Wikipedia grows with an unconventional model of encyclopedia building, "Who writes Wikipedia?" has become one of the questions frequently asked on the project, often with a reference to other Web 2.0 projects such as Digg.[88] Jimmy Wales once argued that only "a community ... a dedicated group of a few hundred volunteers" makes the bulk of contributions to Wikipedia and that the project is therefore "much like any traditional organization". Wales performed a study finding that over 50% of all the edits are done by just .7% of the users (at the time: 524 people). This method of evaluating contributions was later disputed by Aaron Swartz, who noted that several articles he sampled had large portions of their content (measured by number of characters) contributed by users with low edit counts.[89] A 2007 study by researchers from Dartmouth College found that "anonymous and infrequent contributors to Wikipedia ... are as reliable a source of knowledge as those contributors who register with the site."[90] Although some contributors are authorities in their field, Wikipedia requires that even their contributions be supported by published and verifiable sources. The project's preference for consensus over credentials has been labeled "anti-elitism".[11] In August 2007, WikiScanner, a website developed by Virgil Griffith began to trace the sources of changes made to Wikipedia by anonymous editors without Wikipedia accounts. The program revealed that many such edits were made by corporations or government agencies changing the content of articles related to them, their personnel or their work.[91] In a 2003 study of Wikipedia as a community, economics Ph.D. student Andrea Ciffolilli argued that the low transaction costs of participating in wiki software create a catalyst for collaborative development, and that a "creative construction" approach encourages participation.[92] In his 2008 book, The Future of the Internet and How to Stop It, Jonathan Zittrain of the Oxford Internet Institute and Harvard Law School's Berkman Center for Internet & Society cites Wikipedia's success as a case study in how open collaboration has fostered innovation on the web.[93] A 2008 study found that Wikipedia users were less agreeable and open, though more conscientious, than non-Wikipedia users.[94][95] A 2009 study suggested there was "evidence of growing resistance from the Wikipedia community to new content."[96] The Wikipedia Signpost is the community newspaper on the English Wikipedia,[97] and was founded by Michael Snow, an administrator and the current chair of the Wikimedia Foundation board of trustees.[98] It covers news and events from the site, as well as major events from sister projects, such as Wikimedia Commons.[99] Wikimedia Foundation logo

Wikipedia is hosted and funded by the Wikimedia Foundation, a non-profit organization which also operates Wikipedia-related projects such as Wikibooks. The Wikimedia chapters, local associations of Wikipedia users, also participate in the promotion, the development, and the funding of the project. The operation of Wikipedia depends on MediaWiki, a custom-made, free and open source wiki software platform written in PHP and built upon the MySQL database.[100] The software incorporates programming features such as a macro language, variables, a transclusion system for templates, and URL redirection. MediaWiki is licensed under the GNU General Public License and used by all Wikimedia projects, as well as many other wiki projects. Originally, Wikipedia ran on UseModWiki written in Perl by Clifford Adams (Phase I), which initially required CamelCase for article hyperlinks; the present double bracket style was incorporated later. Starting in January 2002 (Phase II), Wikipedia began running on a PHP wiki engine with a MySQL database; this software was custom-made for Wikipedia by Magnus Manske. The Phase II software was repeatedly modified to accommodate the exponentially increasing demand. In July 2002 (Phase III), Wikipedia shifted to the third-generation software, MediaWiki, originally written by Lee Daniel Crocker. Several MediaWiki extensions are installed[101] to extend the functionality of MediaWiki software. In April 2005 a Lucene extension[102][103] was added to MediaWiki's built-in search and Wikipedia switched from MySQL to Lucene for searching. Currently Lucene Search 2,[104] which is written in Java and based on Lucene library 2.0,[105] is used. Overview of system architecture, April 2009. See server layout diagrams on Meta-Wiki.

Wikipedia currently runs on dedicated clusters of Linux servers (mainly Ubuntu),[106][107] with a few OpenSolaris machines for ZFS. As of February 2008, there were 300 in Florida, 26 in Amsterdam, and 23 in Yahoo!'s Korean hosting facility in Seoul.[108] Wikipedia employed a single server until 2004, when the server setup was expanded into a distributed multitier architecture. In January 2005, the project ran on 39 dedicated servers located in Florida. This configuration included a single master database server running MySQL, multiple slave database servers, 21 web servers running the Apache HTTP Server, and seven Squid cache servers. Wikipedia receives between 25,000 and 60,000 page requests per second, depending on time of day.[109] Page requests are first passed to a front-end layer of Squid caching servers.[110] Requests that cannot be served from the Squid cache are sent to load-balancing servers running the Linux Virtual Server software, which in turn pass the request to one of the Apache web servers for page rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages are cached in a distributed memory cache until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Two larger clusters in the Netherlands and Korea now handle much of Wikipedia's traffic load. Wikipedia's original medium was for users to read and edit content using any standard web browser through a fixed internet connection. However, Wikipedia content is now also accessible through offline media, and through the mobile web. On mobile devices access to Wikipedia from mobile phones was possible as early as 2004, through the Wireless Application Protocol (WAP), through the Wapedia service. In June 2007, Wikipedia launched en.mobile.wikipedia.org, an official website for wireless devices. In 2009 a newer mobile service was officially released,[111] located at en.m.wikipedia.org, which caters to more advanced mobile devices such as the iPhone, Android-based devices, or the Palm Pre. Several other methods of mobile access to Wikipedia have emerged (See Wikipedia:Mobile access). Several devices and applications optimise or enhance the display of Wikipedia content for mobile devices, while some also incorporate additional features such as use of Wikipedia metadata (See Wikipedia:Metadata), such as geoinformation.[112] Collections of Wikipedia articles have been published on optical disks. An English version, 2006 Wikipedia CD Selection, contained about 2,000 articles.[113][114] The Polish version contains nearly 240,000 articles.[115] There are also German versions.[116] See also: List of Wikipedias All text in Wikipedia was covered by GNU Free Documentation License (GFDL), a copyleft license permitting the redistribution, creation of derivative works, and commercial use of content while authors retain copyright of their work,[117] up until June 2009, when the site switched to Creative Commons Attribution-ShareAlike (CC-by-SA) 3.0.[118] Wikipedia had been working on the switch to Creative Commons licenses because the GFDL, initially designed for software manuals, is not suitable for online reference works and because the two licenses were incompatible.[119] In response to the Wikimedia Foundation's request, in November 2008, the Free Software Foundation (FSF) released a new version of GFDL designed specifically to allow Wikipedia to relicense its content to CC-BY-SA by August 1, 2009. Wikipedia and its sister projects held a community-wide referendum to decide whether or not to make the license switch.[120] The referendum took place from April 9 to 30.[121] The results were 75.8% "Yes", 10.5% "No", and 13.7% "No opinion".[122] In consequence of the referendum, the Wikimedia Board of Trustees voted to change to the Creative Commons license, effective June 15, 2009.[122] The position that Wikipedia is merely a hosting service has been successfully used as a defense in court.[123][124] Percentage of all Wikipedia articles in English (red) and top ten largest language editions (blue). As of July 2007, less than 23% of Wikipedia articles are in English.

The handling of media files (e.g., image files) varies across language editions. Some language editions, such as the English Wikipedia, include non-free image files under fair use doctrine, while the others have opted not to. This is in part because of the difference in copyright laws between countries; for example, the notion of fair use does not exist in Japanese copyright law. Media files covered by free content licenses (e.g., Creative Commons' cc-by-sa) are shared across language editions via Wikimedia Commons repository, a project operated by the Wikimedia Foundation. There are currently 262 language editions of Wikipedia; of these, 24 have over 100,000 articles and 81 have over 1,000 articles.[1] According to Alexa, the English subdomain (en.wikipedia.org; English Wikipedia) receives approximately 52% of Wikipedia's cumulative traffic, with the remaining split among the other languages (Spanish: 19%, French: 5%, Polish: 3%, German: 3%, Japanese: 3%, Portuguese: 2%).[3] As of July 2008, the five largest language editions are (in order of article count) English, German, French, Polish, and Japanese Wikipedias.[125] Since Wikipedia is web-based and therefore worldwide, contributors of a same language edition may use different dialects or may come from different countries (as is the case for the English edition). These differences may lead to some conflicts over spelling differences, (e.g. color vs. colour)[126] or points of view.[127] Though the various language editions are held to global policies such as "neutral point of view," they diverge on some points of policy and practice, most notably on whether images that are not licensed freely may be used under a claim of fair use.[128][129][130] Contributors for English Wikipedia by country as of September 2006.[131]

Jimmy Wales has described Wikipedia as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language".[132] Though each language edition functions more or less independently, some efforts are made to supervise them all. They are coordinated in part by Meta-Wiki, the Wikimedia Foundation's wiki devoted to maintaining all of its projects (Wikipedia and others).[133] For instance, Meta-Wiki provides important statistics on all language editions of Wikipedia,[134] and it maintains a list of articles every Wikipedia should have.[135] The list concerns basic content by subject: biography, history, geography, society, culture, science, technology, foodstuffs, and mathematics. As for the rest, it is not rare for articles strongly related to a particular language not to have counterparts in another edition. For example, articles about small towns in the United States might only be available in English. Translated articles represent only a small portion of articles in most editions, in part because automated translation of articles is disallowed.[136] Articles available in more than one language may offer "InterWiki" links, which link to the counterpart articles in other editions. Graph showing the number of days between every 10,000,000th edit.

Wikipedia shown in Weird Al's music video for his song "White & Nerdy".

Main article: Wikipedia in culture In addition to logistic growth in the number of its articles,[137] Wikipedia has steadily gained status as a general reference website since its inception in 2001.[138] According to Alexa and comScore, Wikipedia is among the ten most visited websites worldwide.[10][139] Of the top ten, Wikipedia is the only non-profit website. The growth of Wikipedia has been fueled by its dominant position in Google search results;[140] about 50% of search engine traffic to Wikipedia comes from Google,[141] a good portion of which is related to academic research.[142] In April 2007 the Pew Internet and American Life project found that one third of US Internet users consulted Wikipedia.[143] In October 2006, the site was estimated to have a hypothetical market value of $580 million if it ran advertisements.[144] Wikipedia's content has also been used in academic studies, books, conferences, and court cases.[145][146][147] The Parliament of Canada's website refers to Wikipedia's article on same-sex marriage in the "related links" section of its "further reading" list for the Civil Marriage Act.[148] The encyclopedia's assertions are increasingly used as a source by organizations such as the U.S. Federal Courts and the World Intellectual Property Organization[149] - though mainly for supporting information rather than information decisive to a case.[150] Content appearing on Wikipedia has also been cited as a source and referenced in some U.S. intelligence agency reports.[151] In December 2008, the scientific journal RNA Biology launched a new section for descriptions of families of RNA molecules and requires authors who contribute to the section to also submit a draft article on the RNA family for publication in Wikipedia.[152] The Onion newspaper headline "Wikipedia Celebrates 750 Years Of American Independence"

Wikipedia has also been used as a source in journalism,[153] sometimes without attribution, and several reporters have been dismissed for plagiarizing from Wikipedia.[154][155][156] In July 2007, Wikipedia was the focus of a 30-minute documentary on BBC Radio 4[157] which argued that, with increased usage and awareness, the number of references to Wikipedia in popular culture is such that the term is one of a select band of 21st-century nouns that are so familiar (Google, Facebook, YouTube) that they no longer need explanation and are on a par with such 20th-century terms as Hoovering or Coca-Cola. Many parody Wikipedia's openness, with characters vandalizing or modifying the online encyclopedia project's articles. Notably, comedian Stephen Colbert has parodied or referenced Wikipedia on numerous episodes of his show The Colbert Report and coined the related term "wikiality".[57] The site has created an impact upon several forms of media. Some media sources satirize Wikipedia's susceptibility to inserted inaccuracies, such as a front-page article in The Onion in July 2006 with the title "Wikipedia Celebrates 750 Years of American Independence".[158] Others may draw upon Wikipedia's statement that anyone can edit, such as "The Negotiation," an episode of The Office, where character Michael Scott said that "Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject, so you know you are getting the best possible information". Other media sources parody Wikipedia's policies, such as the xkcd strip named "Wikipedian Protester." An xkcd strip entitled "Wikipedian Protester"

Dutch filmmaker IJsbrand van Veelen premiered his 45-minute television documentary The Truth According to Wikipedia in April, 2008.[159] Another documentary film about Wikipedia, entitled Truth in Numbers: The Wikipedia Story, is scheduled for a 2009 release. Shot on several continents, the film will cover the history of Wikipedia and feature interviews with Wikipedia editors around the world.[160][161] On September 28, 2007, Italian politician Franco Grillini raised a parliamentary question with the Minister of Cultural Resources and Activities about the necessity of freedom of panorama. He said that the lack of such freedom forced Wikipedia, "the seventh most consulted website" to forbid all images of modern Italian buildings and art, and claimed this was hugely damaging to tourist revenues.[162] Jimmy Wales receiving the Quadriga A Mission of Enlightenment award

On September 16, 2007, The Washington Post reported that Wikipedia had become a focal point in the 2008 U.S. election campaign, saying, "Type a candidate's name into Google, and among the first results is a Wikipedia page, making those entries arguably as important as any ad in defining a candidate. Already, the presidential entries are being edited, dissected and debated countless times each day."[163] An October 2007 Reuters article, entitled "Wikipedia page the latest status symbol", reported the recent phenomenon of how having a Wikipedia article vindicates one's notability.[164] Wikipedia won two major awards in May 2004.[165] The first was a Golden Nica for Digital Communities of the annual Prix Ars Electronica contest; this came with a €10,000 (£6,588; $12,700) grant and an invitation to present at the PAE Cyberarts Festival in Austria later that year. The second was a Judges' Webby Award for the "community" category.[166] Wikipedia was also nominated for a "Best Practices" Webby. On January 26, 2007, Wikipedia was also awarded the fourth highest brand ranking by the readers of brandchannel.com, receiving 15% of the votes in answer to the question "Which brand had the most impact on our lives in 2006?"[167] In September 2008, Wikipedia received Quadriga A Mission of Enlightenment award of Werkstatt Deutschland along with Boris Tadić, Eckart Höfling, and Peter Gabriel. The award was presented to Jimmy Wales by David Weinberger.[168] In July 2009, BBC Radio 4 broadcast a comedy series called Bigipedia, which was set on a website which was a parody of Wikipedia. Some of the sketches were directly inspired by Wikipedia and its articles.[169] Find more about Wikipedia on Wikipedia's sister projects:Definitions from Wiktionary

Textbooks from Wikibooks

Quotations from Wikiquote

Source texts from Wikisource

Images and media from Commons

News stories from Wikinews

Learning resources from Wikiversity

A number of interactive multimedia encyclopedias incorporating entries written by the public existed long before Wikipedia was founded. The first of these was the 1986 BBC Domesday Project, which included text (entered on BBC Micro computers) and photographs from over 1 million contributors in the UK, and covering the geography, art, and culture of the UK. This was the first interactive multimedia encyclopedia (and was also the first major multimedia document connected through internal links), with the majority of articles being accessible through an interactive map of the UK. The user-interface and part of the content of the Domesday Project have now been emulated on a website.[170] One of the most successful early online encyclopedias incorporating entries by the public was h2g2, which was created by Douglas Adams and is run by the BBC. The h2g2 encyclopedia was relatively light-hearted, focusing on articles which were both witty and informative. Both of these projects had similarities with Wikipedia, but neither gave full editorial freedom to public users. A similar non-wiki project, the GNUPedia project, co-existed with Nupedia early in its history; however, it has been retired and its creator, free software figure Richard Stallman, has lent his support to Wikipedia.[20] Wikipedia has also spawned several sister projects, which are also run by the Wikimedia Foundation. The first, "In Memoriam: September 11 Wiki",[171] created in October 2002,[172] detailed the September 11 attacks; this project was closed in October 2006. Wiktionary, a dictionary project, was launched in December 2002;[173] Wikiquote, a collection of quotations, a week after Wikimedia launched, and Wikibooks, a collection of collaboratively written free books. Wikimedia has since started a number of other projects, including Wikiversity, a project for the creation of free learning materials and the provision of online learning activities.[174] None of these sister projects, however, has come to meet the success of Wikipedia. Some subsets of Wikipedia's information have been developed, often with additional review for specific purposes. For example, the Wikipedia series of CDs/DVDs, produced by Wikipedians and SOS Children (aka "Wikipedia for Schools"), is a free, hand-checked, non-commercial selection from Wikipedia, targeted around the UK National Curriculum and intended to be useful for much of the English speaking world. Wikipedia for Schools is available on-line: an equivalent print encyclopedia would require roughly twenty volumes. There has also been a attempt to put a select subset of Wikipedia's articles into printed book form.[175] Other websites centered on collaborative knowledge base development have drawn inspiration from or inspired Wikipedia. Some, such as Susning.nu, Enciclopedia Libre, and WikiZnanie likewise employ no formal review process, whereas others use more traditional peer review, such as Encyclopedia of Life, Stanford Encyclopedia of Philosophy, Scholarpedia, h2g2, and Everything2. Citizendium, an online encyclopedia, was started by Wikipedia co-founder Larry Sanger in an attempt to create an "expert-friendly" Wikipedia.[176][177][178]

Actually.. i think she maybe right..there are different kinds of ways to answer that question.. depending what you need the answer for.. For example liminations in hairdressing means -

if a client has some sort of condition on their scalp.. e.g dandruff,alopecia, head lice or eczema etc.. depending on what condition the client has or how bad it is jus by looking the hairdresser will no how far she can take the treatment that the clients wants on their hair..so if the client had alopeacia then the hairdresser can carry out a service aslong as they dont use chemical products on the scalp or hair

i think that is right !

Nanotechnology advances affect all branches of engineering and science that deal directly with device components ranging in size between 1/10,000,000 (one ten http://www.answers.com/topic/millionth of a http://www.answers.com/topic/millimeter) and 1/10,0000 millimeter. At these scales, even the most sophisticated microtechnology-based instrumentation is useless. Engineers anticipate that advances in nanotechnology will allow the direct manipulation of molecules in biological samples (e.g., proteins or http://www.answers.com/topic/nucleic-acid) paving the way for the development of new materials that have a biological component or that can provide a biological interface. In addition to new tools, nanotechnology programs advance practical understanding of quantum physics. The internalization of quantum concepts is a necessary component of nanotechnology research programs because the laws of classical physics (e.g., classical mechanics or generalized gas laws) do not always apply to the atomic and near-atomic level. Nanotechnology and quantum physics. Quantum theory and mechanics describe the relationship between energy and matter on the atomic and http://www.answers.com/topic/subatomic scale. At the beginning of the twentieth century, German physicist Maxwell Planck (1858-1947) proposed that atoms absorb or http://www.answers.com/topic/emit electromagnetic radiation in bundles of energy termed quanta. This quantum concept seemed counter-intuitive to well-established Newtonian physics. Advancements associated with quantum mechanics (e.g., the uncertainty principle) also had profound implications with regard to the philosophical scientific arguments regarding the limitations of human knowledge. Planck's quantum theory, which also asserted that the energy of light (a http://www.answers.com/topic/photon) was directly proportional to its frequency, proved a powerful concept that accounted for a wide range of physical phenomena. Planck's constant relates the energy of a photon with the frequency of light. Along with the constant for the speed of light, Planck's constant (h = 6.626 x 10−34 Joule-second) is a fundamental constant of nature. Prior to Planck's work, electromagnetic radiation (light) was thought to travel in waves with an infinite number of available frequencies and wavelengths. Planck's work focused on attempting to explain the limited spectrum of light emitted by hot objects. Danish physicist Niels Bohr (1885-1962) studied Planck's quantum theory of radiation and worked in England with physicists J. J. Thomson (1856-1940), and Ernest Rutherford (1871-1937) to improve their classical models of the atom by incorporating quantum theory. During this time, Bohr developed his model of atomic structure. According to the Bohr model, when an electron is excited by energy it jumps from its ground state to an excited state (i.e., a higher energy orbital). The excited atom can then emit energy only in certain (quantized) amounts as its electrons jump back to lower energy orbits located closer to the nucleus. This excess energy is emitted in quanta of electromagnetic radiation (photons of light) that have exactly the same energy as the difference in energy between the orbits jumped by the electron. The electron quantum leaps between orbits proposed by the Bohr model accounted for Plank's observations that atoms emit or absorb electromagnetic radiation in quanta. Bohr's model also explained many important properties of the http://www.answers.com/topic/photoelectric-effect described by Albert Einstein (1879-1955). Einstein assumed that light was transmitted as a stream of particles termed photons. By extending the well-known wave properties of light to include a treatment of light as a stream of photons, Einstein was able to explain the photoelectric effect. Photoelectric properties are key to regulation of many microtechnology and proposed nanotechnology level systems. Quantum mechanics ultimately replaced electron "orbitals" of earlier atomic models with allowable values for angular momentum (angular velocity http://www.answers.com/topic/multiply by mass) and depicted electron positions in terms of probability "clouds" and regions. In the 1920s, the concept of http://www.answers.com/topic/quantization and its application to physical phenomena was further advanced by more mathematically complex models based on the work of the French physicist Louis Victor de Broglie (1892-1987) and Austrian physicist Erwin Schrödinger (1887-1961) that depicted the particle and wave nature of electrons. De Broglie showed that the electron was not merely a particle but a http://www.answers.com/topic/waveform. This proposal led Schrödinger to publish his wave equation in 1926. Schrödinger's work described electrons as a "standing wave" surrounding the nucleus, and his system of quantum mechanics is called wave mechanics. German physicist Max Born (1882-1970) and English physicist P. A. M. Dirac (1902-1984) made further advances in defining the http://www.answers.com/topic/subatomic-particle (principally the electron) as a wave rather than as a particle and in reconciling portions of quantum theory with relativity theory. Working at about the same time, German physicist Werner Heisenberg (1901-1976) formulated the first complete and self-consistent theory of quantum mechanics. Matrix mathematics was well established by the 1920s, and http://www.answers.com/topic/werner-heisenberg applied this powerful tool to quantum mechanics. In 1926, Heisenberg put forward his uncertainty principle which states that two http://www.answers.com/topic/complementary properties of a system, such as position and momentum, can never both be known exactly. This proposition helped cement the dual nature of particles (e.g., light can be described as having both wave and particle characteristics). Electromagnetic radiation (one region of the spectrum that comprises visible light) is now understood to have both particle and wave like properties. In 1925, Austrian-born physicist Wolfgang Pauli (1900-1958) published the Pauli exclusion principle states that no two electrons in an atom can simultaneously occupy the same quantum state (i.e., energy state). Pauli's specification of spin (+1/2 or −1/2) on an electron gave the two electrons in any http://www.answers.com/topic/suborbital differing quantum numbers (a system used to describe the quantum state) and made completely understandable the structure of the periodic table in terms of electron configurations (i.e., the energy-related arrangement of electrons in energy shells and suborbitals). In 1931, American chemist Linus Pauling published a paper that used quantum mechanics to explain how two electrons, from two different atoms, are shared to make a http://www.answers.com/topic/covalent-bond between the two atoms. Pauling's work provided the connection needed in order to fully apply the new quantum theory to chemical reactions. Advances in nanotechnology depend upon an understanding and application of these fundamental quantum principles. At the quantum level the smoothness of classical physics disappears and nanotechnologies are predicated on exploiting this quantum roughness. Applications The development of devices that are small, light, self-contained, use little energy and that will replace larger microelectronic equipment is one of the first goals of the anticipated nanotechnology revolution. The second phase will be marked by the introduction of materials not http://www.answers.com/topic/feasible at larger than nanotechnology levels. Given the nature of quantum http://www.answers.com/topic/variance, scientists http://www.answers.com/topic/theorize that single molecule sensors can be developed and that sophisticated memory storage and neural-like networks can be achieved with a very small number of molecules. Traditional engineering concepts undergo radical transformation at the atomic level. For example, nano-technology motors may drive gears, the cogs of which are composed of the atoms attached to a carbon ring. Nanomotors may themselves be driven by http://www.answers.com/topic/oscillate magnetic fields or high precision oscillating lasers. Perhaps the greatest promise for nanotechnology lies in potential http://www.answers.com/topic/biotechnology advances. Potential nano-level manipulation of DNA offers the opportunity to radically expand the horizons of genomic medicine and http://www.answers.com/topic/immunology. Tissue-based biosensors may unobtrusively be able to monitor and regulate site-specific medicine delivery or regulate physiological processes. Nanosystems might serve as highly sensitive detectors of toxic substances or used by inspectors to detect traces of biological or chemical weapons. In electronics and computer science, scientists assert that nanotechnologies will be the next major advance in computing and information processing science. Microelectronic devices rely on recognition and flips in electron gating (e.g. where differential states are ultimately represented by a series of binary numbers ["0" or "1"] that depict voltage states). In contrast, future quantum processing will utilize the identity of quantum states as set forth by quantum numbers. In quantum http://www.answers.com/topic/cryptography systems with the ability to http://www.answers.com/topic/decipherment encrypted information will rely on precise knowledge of manipulations used to achieve various atomic states. Nanoscale devices are constructed using a combination of fabrication steps. In the initial growth stage, layers of http://www.answers.com/topic/semiconductor materials are grown on a dimension limiting http://www.answers.com/topic/substrate. Layer composition can be altered to control electrical and/or optical characteristics. Techniques such as http://www.answers.com/topic/molecular-beam-epitaxy (http://www.answers.com/topic/mbe-abbreviation) and metallo-organic chemical vapor deposition (MOCVD) are capable of producing layers of a few atoms thickness. The developed pattern is then imposed on successive layers (the pattern transfer stage) to develop desired three dimensional structural characteristics. Nanotechnology Research In the United States, expenditures on nanotechnology development tops $500 million per year and is largely coordinated by the National Science Foundation and Department of Defense Advanced Research Projects Agency (DARPA) under the umbrella of the National Nano-technology Initiative. Other institutions with dedicated funding for nanotechnology include the Department of Energy (DOE) and National Institutes of Health (NIH). Research interests. Current research interests in nano-technology include programs to develop and exploit nanotubes for their ability to provide extremely strong bonds. Nanotubes can be http://www.answers.com/topic/flex and woven into fibers for use in ultrastrong-but also ultralight-bulletproof vests. Nanotubes are also excellent conductors that can be used to develop precise electronic http://www.answers.com/topic/circuitry. Other interests include the development of nanotechnology-based sensors that allow smarter autonomous weapons capable of a greater range of adaptations http://www.answers.com/topic/en-route to a target; materials that offer stealth characteristics across a broader span of the electromagnetic spectrum; self-repairing structures; and nanotechnology-based weapons to disrupt-but not destroy-electrical system infrastructure. Further Reading Books Mulhall, Douglas. Our Molecular Future: How Nanotechnology, Robotics, Genetics, and Artificial Intelligence Will Change Our World. Amherst, NY: Prometheus Books, 2002. Periodicals Bennewitz, R., et. al., "Atomic scale memory at a silicon surface." Nanotechnology 13 (2000): 499-502. Electronic National Science and Technology Council. "National Nano-technology Initiative." (March 19, 2003).

http://www.answers.com/library/Wikipedia-cid-54347 nanotechnologyhttp://www.answers.com/topic/c60a-png-1 http://www.answers.com/topic/c60a-png-1

Buckminsterfullerene C60, also known as the buckyball, is the simplest of the http://www.answers.com/topic/allotropes-of-carbon known as http://www.answers.com/topic/fullerene. Members of the fullerene family are a major subject of research falling under the nanotechnology umbrella.

Nanotechnology refers broadly to a field of http://www.answers.com/topic/applied-science and technology whose unifying theme is the control of matter on the atomic and http://www.answers.com/topic/molecule scale, normally 1 to 100 nanometers, and the fabrication of devices within that size range. It is a highly http://www.answers.com/topic/interdisciplinarity field, drawing from fields such as http://www.answers.com/topic/applied-physics-1, http://www.answers.com/topic/materials-science, http://www.answers.com/topic/colloid science, http://www.answers.com/topic/semiconductor-device, http://www.answers.com/topic/supramolecular-chemistry, and even http://www.answers.com/topic/mechanical-engineering and http://www.answers.com/topic/electrical-engineering. Much speculation exists as to what new science and technology may result from these lines of research. Nanotechnology can be seen as an extension of existing sciences into the nanoscale, or as a recasting of existing sciences using a newer, more modern term. Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from http://www.answers.com/topic/molecule components which http://www.answers.com/topic/self-assembly chemically by principles of http://www.answers.com/topic/molecular-recognition. In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control. The impetus for nanotechnology comes from a renewed interest in colloidal science, coupled with a new generation of analytical tools such as the http://www.answers.com/topic/atomic-force-microscope (AFM), and the http://www.answers.com/topic/scanning-tunneling-microscope (STM). Combined with refined processes such as http://www.answers.com/topic/electron-beam-lithography and http://www.answers.com/topic/molecular-beam-epitaxy-1, these instruments allow the deliberate manipulation of nanostructures, and led to the observation of novel phenomena. Examples of nanotechnology in modern use are the manufacture of polymers based on molecular structure, and the design of http://www.answers.com/topic/integrated-circuit layouts based on surface science. Despite the great promise of numerous nanotechnologies such as http://www.answers.com/topic/quantum-dot and http://www.answers.com/topic/carbon-nanotube, real commercial applications have mainly used the advantages of colloidal nanoparticles in bulk form, such as http://www.answers.com/topic/sunscreen, http://www.answers.com/topic/cosmetic, http://www.answers.com/topic/industrial-coating, and stain resistant clothing.

Nanotechnology

c60a-png-1

{| ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Topics | http://www.answers.com/topic/history-of-nanotechnology · http://www.answers.com/topic/implications-of-nanotechnology

http://www.answers.com/topic/list-of-nanotechnology-applications · http://www.answers.com/topic/list-of-nanotechnology-organizations

http://www.answers.com/topic/nanotechnology-in-fiction · http://www.answers.com/topic/list-of-nanotechnology-topics ! style="BACKGROUND: #e6e6e6; COLOR: #000000; LINE-HEIGHT: 11pt" | Subfields and related fields | http://www.answers.com/topic/nanomedicine

molecular-self-assembly-1

molecular-electronics

scanning-probe-microscopy

nanolithography

http://www.answers.com/topic/molecular-nanotechnology ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Nanomaterials | http://www.answers.com/topic/nanomaterials · http://www.answers.com/topic/fullerene

carbon-nanotube

nanotube-membrane

fullerene-chemistry

http://www.answers.com/topic/potential-applications-of-carbon-nanotubes · http://www.answers.com/topic/fullerenes-in-popular-culture

http://www.answers.com/topic/timeline-of-carbon-nanotubes · http://www.answers.com/topic/allotropes-of-carbon

http://www.answers.com/topic/nanoparticle · http://www.answers.com/topic/quantum-dot

http://www.answers.com/topic/colloidal-gold · http://www.answers.com/topic/colloidal-silver ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Molecular nanotechnology | http://www.answers.com/topic/molecular-assembler

mechanosynthesis

http://www.answers.com/topic/nanorobotics · http://www.answers.com/topic/grey-goo

k-eric-drexler

engines-of-creation ----

: Main article: http://www.answers.com/topic/history-of-nanotechnology The first use of the distinguishing concepts in 'nanotechnology' (but predating use of that name) was in "http://www.answers.com/topic/there-s-plenty-of-room-at-the-bottom," a talk given by physicist http://www.answers.com/topic/richard-feynman at an http://www.answers.com/topic/american-physical-society meeting at http://www.answers.com/topic/california-institute-of-technology on http://www.answers.com/topic/december-29, http://www.answers.com/topic/1959. Feynman described a process by which the ability to manipulate individual atoms and molecules might be developed, using one set of precise tools to build and operate another proportionally smaller set, so on down to the needed scale. In the course of this, he noted, scaling issues would arise from the changing magnitude of various physical phenomena: gravity would become less important, surface tension and http://www.answers.com/topic/van-der-waals-force-1 would become more important, etc. This basic idea appears feasible, and exponential assembly enhances it with http://www.answers.com/topic/angle-of-parallelism to produce a useful quantity of end products. The term "nanotechnology" was defined by http://www.answers.com/topic/tokyo-university-of-science Professor http://www.answers.com/topic/norio-taniguchi in a http://www.answers.com/topic/1974 paper (N. Taniguchi, "On the Basic Concept of 'Nano-Technology'," Proc. Intl. Conf. Prod. Eng. Tokyo, Part II, Japan Society of Precision Engineering, 1974.) as follows: "'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or by one molecule." In the 1980s the basic idea of this definition was explored in much more depth by http://www.answers.com/topic/k-eric-drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and the books http://www.answers.com/topic/engines-of-creation (1986) and Nanosystems: Molecular Machinery, Manufacturing, and Computation, (1998, ISBN 0-471-57518-6), and so the term acquired its current sense. Nanotechnology and nanoscience got started in the early 1980s with two major developments; the birth of http://www.answers.com/topic/cluster-physics science and the invention of the http://www.answers.com/topic/scanning-tunneling-microscope (STM). This development led to the discovery of http://www.answers.com/topic/fullerene in 1986 and http://www.answers.com/topic/carbon-nanotube a few years later. In another development, the synthesis and properties of semiconductor http://www.answers.com/topic/nanocrystal was studied. This led to a fast increasing number of metal oxide nanoparticles of http://www.answers.com/topic/quantum-dot. The http://www.answers.com/topic/atomic-force-microscope was invented five years after the STM was invented. The AFM uses atomic force to see the atoms. http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AWikibooks-logo-en.svg

Wikibooks' [[wikibooks:|]] has more about this subject: The Opensource Handbook of Nanoscience and Nanotechnology

One nanometer (nm) is one billionth, or 10-9 of a meter. For comparison, typical carbon-carbon http://www.answers.com/topic/bond-length, or the spacing between these atoms in a molecule, are in the range .12-.15 nm, and a http://www.answers.com/topic/dna double-helix has a diameter around 2 nm. On the other hand, the smallest http://www.answers.com/topic/cell lifeforms, the bacteria of the genus http://www.answers.com/topic/mycoplasma-2, are around 200 nm in length. To put that scale in to context the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earthhttp://www.answers.com/topic/nanotechnology#wp-_note-NationalG. Or another way of putting it: a nanometer is the amount a man's beard grows in the time it takes him to raise the razor to his facehttp://www.answers.com/topic/nanotechnology#wp-_note-NationalG. Image:Atomic resolution Au100.JPG‎ Image of http://www.answers.com/topic/surface-reconstruction on a clean http://www.answers.com/topic/gold(http://www.answers.com/topic/miller-index) surface, as visualized using http://www.answers.com/topic/scanning-tunneling-microscope. The individual http://www.answers.com/topic/atom composing the surface are visible.

: Main article: http://www.answers.com/topic/nanomaterials A number of physical phenomena become noticeably pronounced as the size of the system decreases. These include http://www.answers.com/topic/statistical-mechanics effects, as well as http://www.answers.com/topic/quantum-mechanics effects, for example the "http://www.answers.com/topic/quantum size effect" where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached. Additionally, a number of http://www.answers.com/topic/physical-property-2 change when compared to macroscopic systems. One example is the increase in surface area to volume of materials. This catalytic activity also opens potential risks in their interaction with http://www.answers.com/topic/biomaterial. Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent (copper); inert materials become catalysts (platinum); stable materials turn combustible (aluminum); solids turn into liquids at room temperature (gold); insulators become conductors (silicon). A material such as http://www.answers.com/topic/gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale.

: Main article: http://www.answers.com/topic/molecular-self-assembly-1 Modern http://www.answers.com/topic/chemical-synthesis has reached the point where it is possible to prepare small http://www.answers.com/topic/molecule to almost any structure. These methods are used today to produce a wide variety of useful chemicals such as http://www.answers.com/topic/drug or commercial http://www.answers.com/topic/polymer. This ability raises the question of extending this kind of control to the next-larger level, seeking methods to assemble these single molecules into http://www.answers.com/topic/supramolecular-assembly consisting of many molecules arranged in a well defined manner. These approaches utilize the concepts of http://www.answers.com/topic/molecular-self-assembly-1 and/or http://www.answers.com/topic/supramolecular-chemistry to automatically arrange themselves into some useful conformation through a http://www.answers.com/topic/bottom-up-2 approach. The concept of http://www.answers.com/topic/molecular-recognition is especially important: molecules can be designed so that a specific conformation or arrangement is favored due to http://www.answers.com/topic/noncovalent-bonding http://www.answers.com/topic/intermolecular-force. The Watson-Crick http://www.answers.com/topic/base-pair rules are a direct result of this, as is the specificity of an http://www.answers.com/topic/enzyme being targeted to a single http://www.answers.com/topic/substrate-biochemistry, or the specific http://www.answers.com/topic/protein-folding itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole. Such bottom-up approaches should, broadly speaking, be able to produce devices in parallel and much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in http://www.answers.com/topic/biology-3, most notably http://www.answers.com/topic/base-pair and http://www.answers.com/topic/enzyme-http://www.answers.com/topic/substrate-biochemistry interactions. The challenge for nanotechnology is whether these principles can be used to engineer novel constructs in addition to natural ones.

: Main article: http://www.answers.com/topic/molecular-nanotechnology Molecular nanotechnology, sometimes called molecular manufacturing, is a term given to the concept of engineered nanosystems (nanoscale machines) operating on the molecular scale. It is especially associated with the concept of a http://www.answers.com/topic/molecular-assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of http://www.answers.com/topic/mechanosynthesis. Manufacturing in the context of productive nanosystems is not related to, and should be clearly distinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubes and nanoparticles. When the term "nanotechnology" was independently coined and popularized by http://www.answers.com/topic/k-eric-drexler (who at the time was unaware of an http://www.answers.com/topic/history-of-nanotechnology by http://www.answers.com/topic/norio-taniguchi) it referred to a future manufacturing technology based on http://www.answers.com/topic/molecular-machine-1 systems. The premise was that molecular-scale biological analogies of traditional machine components demonstrated molecular machines were possible: by the countless examples found in biology, it is known that billions of years of evolutionary feedback can produce sophisticated, http://www.answers.com/topic/stochastic optimised biological machines. It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using http://www.answers.com/topic/bionics principles. However, Drexler and other researchers have proposed that advanced nanotechnology, although perhaps initially implemented by biomimetic means, ultimately could be based on mechanical engineering principles, namely, a manufacturing technology based on the mechanical functionality of these components (such as gears, bearings, motors, and structural members) that would enable programmable, positional assembly to atomic specification (PNAS-1981). The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems. But Drexler's analysis is very qualitative and does not address very pressing issues, such as the "fat fingers" and "Sticky fingers" problems. In general it is very difficult to assemble devices on the atomic scale, as all one has to position atoms are other atoms of comparable size and stickyness. Another view, put forth by Carlo Montemagno, is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Yet another view, put forward by the late http://www.answers.com/topic/richard-smalley, is that mechanosynthesis is impossible due to the difficulties in mechanically manipulating individual molecules. This led to an exchange of letters in the http://www.answers.com/topic/american-chemical-society publication Chemical & Engineering News in 2003. Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube http://www.answers.com/topic/nanomotor, a molecular actuator, and a nanoelectromechanical relaxation oscillator. An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at http://www.answers.com/topic/cornell-university in 1999. They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage. http://www.answers.com/topic/nanocartriangle-jpg-1 http://www.answers.com/topic/nanocartriangle-jpg-1

Space-filling model of the http://www.answers.com/topic/nanocar on a surface, using http://www.answers.com/topic/fullerene as wheels.

http://www.answers.com/topic/rotaxane-jpg-1 http://www.answers.com/topic/rotaxane-jpg-1

Graphical representation of a http://www.answers.com/topic/rotaxane, useful as a molecular switch.

http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AAchermann7RED.jpg http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AAchermann7RED.jpg

This device transfers energy from nano-thin layers of http://www.answers.com/topic/quantum-well to http://www.answers.com/topic/nanocrystal above them, causing the nanocrystals to emit visible light. [1]

As nanotechnology is a very broad term, there are many disparate but sometimes overlapping subfields that could fall under its umbrella. The following avenues of research could be considered subfields of nanotechnology. This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions. * http://www.answers.com/topic/colloid science has given rise to many materials which may be useful in nanotechnology, such as http://www.answers.com/topic/carbon-nanotube and other http://www.answers.com/topic/fullerene, and various http://www.answers.com/topic/nanoparticle and http://www.answers.com/topic/nanorod. * http://www.answers.com/topic/nanomaterials can also be used for bulk applications; most present commercial applications of nanotechnology are of this flavor. * Progress has been made in using these materials for medical applications; see nanomedicine. These seek to arrange smaller components into more complex assemblies. * DNA Nanotechnology utilises the specificity of http://www.answers.com/topic/base-pair to construct well-defined structures out of http://www.answers.com/topic/dna and other http://www.answers.com/topic/nucleic-acid. * More generally, molecular-self-assembly-1 seeks to use concepts of http://www.answers.com/topic/supramolecular-chemistry, and http://www.answers.com/topic/molecular-recognition in particular, to cause single-molecule components to automatically arrange themselves into some useful conformation. These seek to create smaller devices by using larger ones to direct their assembly. * Many technologies descended from conventional semiconductor-device-fabricationfor fabricating http://www.answers.com/topic/microprocessor are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology. http://www.answers.com/topic/giant-magnetoresistance-1-based hard drives already on the market fit this description,http://www.answers.com/topic/nanotechnology#wp-_note-0 as do http://www.answers.com/topic/atomic-layer-deposition (ALD) techniques. http://www.answers.com/topic/peter-gr-nberg and http://www.answers.com/topic/albert-fert received http://www.answers.com/topic/nobel-prize-in-physics for their discovery of Giant magnetoresistance and contributions to the field of spintronics in 2007.http://www.answers.com/topic/nanotechnology#wp-_note-1 * Solid-state techniques can also be used to create devices known as nanoelectromechanical-systemsor NEMS, which are related to http://www.answers.com/topic/microelectromechanical-systems or MEMS. * http://www.answers.com/topic/atomic-force-microscope tips can be used as a nanoscale "write head" to deposit a chemical on a surface in a desired pattern in a process called dip-pen-nanolithography. This fits into the larger subfield of http://www.answers.com/topic/nanolithography. These seek to develop components of a desired functionality without regard to how they might be assembled. * molecular-electronics seeks to develop molecules with useful electronic properties. These could then be used as single-molecule components in a nanoelectronic device. For an example see http://www.answers.com/topic/rotaxane. * Synthetic chemical methods can also be used to create synthetic-molecular-motors, such as in a so-called http://www.answers.com/topic/nanocar. |}