Colors that can be combined to make a wide range of colors are called Primary colors. Humans generally consider three colors as primary because human color vision is trichromatic. Which means a human eye has only three types of color receptors generally called as cone cells. Each cone cell senses different ranges of color spectrum.
Additive Primary Colors:
The colors Red, Green and Blue are generally termed as the additive primary colors. When we add equal amounts of light of these colors, white light is evolved. Simply, humans can see white light when we add these colors, so they are called as additive primary colors.
Subtractive Primary Colors
The colors cyan, yellow, and magenta are also generally called as subtractive primary colors. When we subtract the primary additive colors viz. red, green, and blue from white light the, each of these (subtractive primaries) are formed. Therefore they are called as subtractive primary colors.
However the choice of primary colors is different for different people in different fields. Additive primary colors are widely used in television and computer video displays. Whereas, the subtractive colors Cyan, Magenta, and yellow are used in printing industry.
