For the human eye, the best primary colors of light are Red, Green, and Blue. Combining the wavelengths of light we see as these colors produces the greatest range of visible color.
| green | (●) | + | red | (●) | = | yellow | (●) | ||
| red | (●) | + | blue | (●) | = | magenta | (●) | ||
| blue | (●) | + | green | (●) | = | cyan | (●) | ||
That is, the primary and secondary RGB colors (with secondary colors in boldface) are:
green | yellow | red | magenta | blue | cyan | green |
Because color is defined as the wavelengths of the emitted light, combining RGB colors means adding light (thus the term "additive color"), and the combinations are brighter. When all three primaries (or for that matter all three secondaries) are combined in equal amounts, the result is white.
The RGB secondary colors produced by the addition of light turn out to be the best primary colors for pigments, the mixing of which subtracts light.