The CMYK color model (also known as process color, or four color) is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key (black).

CMYK is not supported in HTML, but it is suggested as a new standard in CSS4. While waiting for CSS4, you can include W3Schools' Color library, and use CMYK as an HTML attribute like this

CMYK dots via SkillUp. In RGB color spaces, all primaries combine to produce Notice how the CMYK sliders differ from the RGB sliders. Zero intensity of all primaries produces black in RGB color profiles...