dpi means dots per inch. If you were to print a straight line one inch long using the max print setting (600 dpi for your printer) that line would consist of 600 dots. Fairly high quality image
LPI - Lines Per Inch - Refers to the number of lines of text a printer will fit in an inch of paper. (the smaller the font size the more lines per inch) DPI - Dots Per Inch - The number of dots a printer can put within an inch of paper (the smaller the print nozzles the more DPI' PPI - Pixels Per Inch - usually relates to the resolution of a monitor.
The physical size of a pixel is going to depend on the resolution of the device displaying it. Resolution is typically measured in Dots per Inch (DPI). The general formula to convert from pixels to inches is: Pixels / DPI = Size in Inches. For example, at 75 DPI (typical CRT display) 300px would be 4 inches; while at 150DPI (typical cell phone display) 300px would be 2 inches.
Simply because the dots are smaller ! The nozzles in a 1200 dpi printer are half the diameter of those in a 600 dpi printer. This allows for greater accuracy in the printed picture, and smoother curves etc.
Using the example in the comment, the Archos is a 7 inches screen, while the Nexus One has a 3.7 inches screen. At the same number of pixels, the density of pixels is double on the Nexus One. Remember, dpi means dots per inch. That means that the same image would be rendered twice as big in the Archos than in the Nexus One.
Ah, the touchpad is a wonderful tool that allows us to navigate our digital world with ease. Its advantages include convenience, precision, and portability. However, some may find it less precise than a mouse and it can sometimes lead to accidental clicks or movements. Remember, it's all about finding what works best for you and embracing the happy little accidents along the way.