CMYK (Cyan-Magenta-Yellow-blacK) representation of color is of the form cmyk(C%, M%, Y%, K%), where C, M, Y, and K are the percent values for the cyan, magenta, yellow, and black values of the color. The CMYK color system is used in the printing industry. The CMYK system is NOT used in HTML or style sheets, but is a popular form of color representation, and it gives you an insight into color representation.
Color swatches are defined by using the hexadecimal code for the color and are sorted by CMYK. The color names are descriptive and shouldn’t be used to specify a color unless you are using the 16 named colors or SVG colors.