First thing first - color is a measurement that can be viewed in many different units. Much like temperature can be measured in Fahrenheit and Celsius. In color we have: RGB . When we print something we typically use CMYK {Cyan, Magenta, Yellow, Black}. When we add these together we get black. These are also the secondary colors to RGB. The color wheel above represents both RGB and CMYK colors but only denotes RGB and hue degrees. I've also posted all of my color theory sheets on flickr if...