A colour model that describes each colour in terms of the

quantity of each secondary colour (cyan, magenta, yellow), and

"key" (black) it contains. The CMYK system is used for

printing. For mixing of pigments, it is better to use the

secondary colours, since they mix subtractively instead of

additively. The secondary colours of light are cyan, magenta

and yellow, which correspond to the primary colours of pigment

(blue, red and yellow). In addition, although black could be

obtained by mixing these three in equal proportions, in

four-colour printing it always has its own ink. This gives

the CMYK model. The K stands for "Key' or 'blacK,' so as not

to cause confusion with the B in RGB.