CMYK is an abbreviation for cyan, magenta, yellow and black. These are the four standard colours used in process printing and are called process colours.
In commercial offset printing, a printing plate is made for each of the process colours. The four plates are then used to print each individual colour on a sheet of paper. Tiny dots of the four colours when combined reproduce the original colour image.
The principle is much the same for digital printing. When you replace the ink or toner cartridges in your desktop or office printer, you’ll find there is usually one cartridge for each of the process colours.
