Working with images destined for the screen or the Web, we designate colors by the amount of red, green, or blue in the color. In your graphics software these numbers might look like this: 255 RED 255 GREEN 0 BLUE. A number between 1-255 designates the amount of each RGB color.
In order for your computer to understand these numbers we translate them into 6 digit hexidecimal numbers or triplets. 255 RED 255 GREEN 0 BLUE becomes FFFF00. The first pair (FF) is the Red, The second pair (FF) is the Green, and 00 is the Blue. FF is the hexidecimal equivalent of 255 and 00 is the hexidecimal equivalent of 0.
RGB is the most common color mode used when creating graphics, even though graphics to be commercially printed are eventually converted to CMYK mode, the colors used in printing inks.

