The Prang color system is the basis of the artist's color wheel, and it uses red, blue and yellow as its primaries. This system theorizes that the three primary colors can't be produced by mixing other hues, but can produce all other hues through mixing two of the primaries together.
Developed by Louis Prang, the Prang color system is most often used by artists in determining what paint pigments to mix in order to produce desired colors out of the basic primary colors.
Many other color systems are used. Printers rely on the process color system, which uses cyan, magenta, yellow and black as its primary colors. Televisions, computer monitors and other devices that project light to represent color use the additive system, which mixes red, blue and green primary colors.