CMYK (cyan, magenta, yellow, black) color model refers to the four color components frequently used in printed media such as books, magazines, brochures, and ink-jet printing to produce full-color images.
Adding together the four colors in varying quantity produces millions of visible colors. Not all colors can be faithfully reproduced, however, due to limitations of inks, the printing process, and paper characteristics.
CMYK color is the standard color model for documents produced for print, through there are other color models. Providing images in CMYK color mode often limits flexibility for image manipulation, color correction, delivery via digital media, and conversion for use in digital media.
Modern graphics software allows documents to be fully produced using RGB images, with conversion to CMYK occurring immediately prior to printing, under the control of the printing vendor.
Alternate color models include RGB, Grayscale, and Lab.