The laws concerning what Jews can and cannot do on the Sabbath (Shabbat in Hebrew or Shabbos in Yiddish) are complex - so much so that rabbis still discuss the matter even after all these thousands of years, not least of all because new technology requires new guidelines.

In brief, activities which are not permitted include travelling in a motorised vehicle; writing; laundry; using the telephone; any form of business transaction; kindling fire - this includes activities such as cooking, for which a process of producing heat must be instigated, and switching electrical appliances on or off); gardening. These raise certain complexities - for example, while a refrigerator may be used the internal light must be disabled since if it turns on when the fridge is opened you have kindled fire by switching on a device that produces heat and thus "kindled fire." However, it does not mean that Jews spend their Shabbat sitting in dark and cold houses, being miserable - indeed, quite the opposite: Jews prepare for the Shabbat in advance and celebrate in luxury. Many look forward to cholent, a traditional and very popular dish which is made during the Friday daytime before Shabbat begins, cooked slowly and consumed on the Saturday (it's delicious, and every family has its own version).

Slightly more complex are the laws regarding muktzah, items which may not be moved - either by direct or indirect contact - during Shabbat. However, moving them in an unusual or accidental way is permitted - such as with the teeth. Examples of muktzah include those items that have no designated use - such as plants, stones, a twig on the ground - as well as those items that have only one designated use (and are usually valuable) - for example, a camera, certain certificates and documents (including passports, which can be tricky when travelling), a television. Muktzah also includes items which are expressly forbidden by the Torah, including treif (non-kosher) food, and items associated with those activities forbidden during Shabbat such as pens, matches and so on. Also banned is the carrying of any item from a private place - such as a home - to a public place, such as a park. This applies to any item; meaning that - as an example - a pram or wheelchair cannot be used during Shabbat since it must be transported from the home (private) into the street (public). As a result, areas with a high Jewish population often establish an eiruv whereby a large area - which may be several streets - becomes designated a private place, allowing inhabitants to bypass this law.

Every Jew is not just permitted to break Shabbat rules if harm will arise as a result of not doing so, but expected to. Thus, a Jew would be allowed to use a car to take an injured person to hospital despite the law against driving as human life and wellbeing is considered to always take precedence against all other laws. Similarly, if a Jew has neglected to light a fire prior to Shabbat but it unexpectedly becomes cold and somebody within the home may suffer ill as a result - ie; children, the inform, the elderly - then he or she is both permitted and expected to light a fire.

It all sounds very complex - and it is - but it's remarkable how quickly you get used to it!