The process colors most widely used to print 'full color' are the four inks in the subtractive color system -- cyan, magenta, yellow and black.
Subtractive color describes the color of inks. The complementary colors are red, green and blue. Combining the three primary colors creates a brown-black.
The also contains light shades of cyan and magenta ink, for a wider range of colors. This system is denoted by the letters CMYKcm.