Spot colors are pre-mixed inks and only use one ink fountain. This is used in offset printing for paper products and screen printing.  Process colors are four ink colors (cyan, magenta, yellow and black), which are printed together on one sheet in a distinct pattern that enables the eye to see thousands of shades of colors. This process is used for small runs of paper products, banners, stickers and many signs. There are quality and cost advantages to using process colors and to using spot colors, depending on the job.