When you mix colors using paint, or through the printing process, you are using the subtractive color method. The primary colors of light are red, green, and blue. If you subtract these from white you get cyan, magenta, and yellow. Mixing the colors generates new colors as shown on the color wheel, or the circle on the right. Mixing these three primary colors generates black. As you mix colors, they tend to get darker, ending up as black. The CMYK color system (cyan, magenta, yellow, and black) is the color system used for printing.