A spot color is a special premixed ink that is used in printing in addition to CMYK process inks, and requires its own plate on a printing press. Spot colors are used when only a few colors are necessary in a design and can accurately reproduce colors that are outside the gamut of process colors. They are not determined by altered color values or by color management, and follow a spot color matching system such as Pantone, Inc. Each spot color used will generate an additional spot color printing plate for a printing press, increasing printing costs. If you think your design may require more than four colors, consider printing the document using process colors (CMYK).
Pantone®, Pantone Matching System and PMS are Pantone, Inc’s standard trademarks for color standards, color data, color reproduction and color reproduction materials, and other color related products and services, meeting its specifications, control and quality requirements. Using Pantone colors will produce consistent color from more than one printer/supplier. Colors are normally referred to by a corresponding number on the Pantone palette.
CMYK stands for the ink colors Cyan, Magenta, Yellow and Black, used in process color printing. CMYK is the standard color model used in offset printing full-color documents. When using the inks of these four basic colors, certain percentages of these colors can be added and subtracted to yield a variety of new colors. Combining 100% of all four colors together will yield black, while subtracting all the colors will yield white, or the color of the paper stock.