Additive Light - RGB - Red Green Blue

The (agreed upon) base colors red green and blue add up to white.

Additive Color

Source Commons.wikimedia.org AdditiveColorMixiing.svg

Subtractive Light - CMY - Cyan Magenta Yellow

Objects subtract colors from light (white background). For example, a magenta object subtracts cyan and yellow. Subtracting all colors results in black.

Subtractive Colors

Source Commons.wikimedia.org CMY_ideal_version.svg