What are CMYK codes?
The abbreviation 'CMYK' stands for Cyan, Magenta, Yellow and BlacK (or Key) and is mainly used for printing inks. A large number of colors can be made by mixing these 4 basic colors. The CMYK code of a color indicates the coverage rate of the 4 inks that are needed to obtain that color. More information about CMYK can be found on Wikipedia.