Billiard balls are spherical objects used in cue sports like pool, snooker, and carom. Typically made of resin or plastic, they come in various colors and sizes, with the standard diameter being about 2.25 inches for pool balls. Each ball has a specific number or color that designates its role in the game. In a standard game of pool, there are 16 balls: one cue ball and 15 object balls, which include 7 solid-colored balls, 7 striped balls, and the 8-ball. Players use a cue stick to strike the cue ball, aiming to pocket the object balls into the table's pockets.