The bright colors of the 15 pool balls look nice on the green felt, but the colors also mean something. Each numbered ball has a designated color. Once you become familiar with them, you don't need to walk to the other end of the table to get a look at the number printed on the ball; you can call your shot just by looking at its color.
Balls that are numbered one through eight are one solid color, except for a small circle with the number in it. The one ball is yellow; two is blue; three is red; four is purple; five is orange; six is green; seven is burgundy; and the eight ball, as most people know, is black.
All of the solid balls except the eight have a striped counterpart for balls numbered nine to 15. These balls' base color is white, with a wide colored stripe going around the middle. The numbers are printed on the white part. Nine has a yellow stripe; 10 is blue; 11 is red; 12 is purple; 13 is orange; 14 is green; and 15 is burgundy. If you learn the colors of the solid balls, just add eight to the number to find its corresponding striped ball. For example, the two ball is blue. Two plus eight is 10, so the 10 ball has a blue stripe.
The cue ball, the one you strike with your pool stick to hit your object ball, completes the set. It is always white. Some cue balls have one small red dot on them, to help you practice your aim. Others have several red dots on them, which allow you to see the ball's spin as it makes its way across the table.
Occasionally a set of pool balls will have pink on the three and 11 balls, or tan for the seven and 15 balls. Some sets come with all balls in pastel versions of the normal colors, though this is not common in public venues such as bars and pool halls.
If you have your own pool table want a personalized touch, balls can be customized with your name or symbols. They are available in glow-in-the-dark, pearlized, crystal or marbleized. You can also get them with the logo of your favorite college sports team.