There are various ways to categorize colors. The term color space is commonly used.
RGB (Red, Green, and Blue) is considered to be the native computer color space and is used for displaying images on screen. CYMK (Cyan, Magenta Yellow, and Black) color space is able to print all colors; it is mostly used for commercial printing and used by most computer printers.HSL (Hue, Saturation, Lightness) and HSV (Hue, Saturation, Value) are two concepts based on the light and intensity factors; used for the representation of points in a RGB colors space and providing a better color relationship than RGB.
Here below is a link providing algorithms for these color conversion: