RGB color model

RGB (red, green, and blue) refers to a system for representing the colors to be used on a computer display.
Red, green, and blue can be combined in various proportions to obtain any color in the visible spectrum. Levels of R, G, and B can each range from 0 to 100 percent of full intensity.

Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors.