Billiard ball
（重定向自Cueball）
![Cue balls from (left to right): Russian pool and kaisa—68 mm (2 11⁄16 in)Carom—61.5 mm (2 7⁄16 in)American-style pool—57.15 mm (2 1⁄4 in)British-style pool (largish) —56 mm (2 3⁄16 in)Snooker—52.5 mm (2 1⁄15 in)Scaled-down pool—51 mm (2 in) for portable miniature tables
Not shown: half-scale children's miniature pool—approximately 28.5 mm (1 1⁄8 in).](/Images/godic/202501/07/Billiard_ball_comparison1420.jpg")
![A standard set of carom billiards balls (61.5 mm [2 7⁄16 in] diameter), including a red object ball, a plain white cue ball, and a dotted cue ball for the opponent. Some games use an additional object ball.](/Images/godic/202501/07/Carom_billiards_balls1420.jpg")
![Classic-style pool balls racked for a game of ten-ball, just before the break shot.](/Images/godic/202501/07/Billiard_Balls_and_Rack1420.jpg")
![Modern-style pool balls](/Images/godic/202501/07/Billiards_balls1420.jpg")
A billiard ball is a small, hard ball used in cue sports, such as carom billiards, pool, and snooker. The number, type, diameter, color, and pattern of the balls differ depending upon the specific game being played. Various particular ball properties such as hardness, friction coefficient and resilience are important to accuracy.