4C (CMYK) Printing is often known as full colour printing also.
CMYK is an acronym for Cyan, Magenta, Yellow and Black. CMYK refers to the 4 primary colors of pigment used in 4 Color Process Printing. The CMYK color model also describes the full color printing process itself. In full color printing, every image is color separated into Cyan, Magenta, Yellow and Black in specific dot patterns that vary in size and frequency to create a combination of ay color with a fraction of the ink.
Example of 4C (CMYK) printing: