Unless you use colors from the 'browser safe' palette, you can't be sure that the colors you see on your screen will appear the same way on other people's monitors. On-screen which, say, is only displaying 256 colors, colors not from the browser safe palette will be dithered, i.e., made up of dots of a combination of colors which best approximate the color which cannot be displayed.
If you're creating backgrounds and simple line-drawn graphics, buttons etc., then you would do well to only use those colors from the browser safe palette. You will recognize these from their RGB (red/green/blue) codes which will each be some combination of hex: 00, 33, 66, 99 CC, FF or decimal: 00, 51, 102, 153, 204, 255.
You'll find a great explanation of the 216 color palette at http://www.onr.com/user/lights/netcol.html - you can also find the RGB color chart here and the hexidecimal color chart here.
For more charts and info, see Doug’s site at http://home.flash.net/~drj2142/index.html
At Granite, we optimize all graphics for maximum download speed and color accuracy. - Updated:
CATEGORY
RESULTS 
Knowledge
Base 
