Short for
Cyan-Magenta-Yellow-Black, and pronounced as separate letters. CMYK is a color model in which all colors are described as a mixture of these four
process colors. CMYK is the
standard color model used in
offset printing for full-color
documents. Because such printing uses inks of these four basic colors, it is often called
four-color printing.
In contrast, display devices generally use a different color model called RGB, which stands for Red-Green-Blue. One of the most difficult aspects of desktop publishing in color is color matching -- properly converting the RGB colors into CMYK colors so that what gets printed looks the same as what appears on the monitor.
Also see The Science of Color in the Did You Know . . . ? section of Webopedia.
