Does 600 dpi or 1200 dpi give better picture quality?

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...

It's because dpi stands for 'dots per inch', so a printer that can do more dots per inch can produce finer detail on the printed page.

First of all DPI stands for Dots Per Inch which is more often assocated with the resolution that a printer can print at. When refering to digital cameras DPI is also a measurement of resolution....

1200 dpi because dpi stands for dot per inch, there for 1200 dpi gives 1200 dots per inch instead of 600 dpi only giving 600 dots per inch thus 1200 dpi gives a better resolution

dpi is dots per inch. 400 * 600 dpi is the number of ink dots per square inch that are produced by a computer printer.