A number between 1-255 designates the amount of each color RED, GREEN, or BLUE.
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.
In print, we try to reproduce the colors we see. Remember how color (light) is made by subtracting differing amounts of other colors from the additive primaries (RGB)? Well, in printing when we are mixing (adding) inks together the colors don't come out as we might expect.
Therefore, we start with the subtractive primaries (CYM) and mix those in varying amounts (plus BLACK abbreviated as K) to get the colors we see printed in magazines and books.
Colors are mixed in percentages such as:
50% CYAN 100% YELLOW 25% MAGENTA 
This CMY(K) color model is only one of many ways we can express color for print — but we'll save that topic for another feature.
There are other color-related terms which we'll address briefly. The overview on the next page will help you see how the different terms work together and interact to describe the colors we see in the world, in print, and on the Web.
