Under World Pool-Billiard Association (WPA) official equipment specifications, pool balls weigh from 5.5 to 6 oz (160 to 170 g) and have a diameter of 2.25 inches (57 mm), plus or minus 0.005 inches (0.13 mm). The World Pool-Billiard Association (WPA) publishes the world standardized rules. The largest nine-ball tournaments are the US Open Nine-ball Championship and the WPA World Nine-ball Championship for men and women. Of these, 10 ball billiards rules nine-ball is the most popular and the predominant professional game with ten-ball as the second-most prominent. There are many local and regional tours and tournaments that are contested with nine-ball. There are three balls. The table has six pockets along the rails, into which balls are shot. Pool is played on a six pocket table. Rotation games require players to make legal contact with the lowest numbered ball on the table or a foul is called. In a variety of the game called three-cushion billiards, the cue ball must also touch a cushion or cushions three or more times to complete a carom.

Balls may bounce on the cushion tops and rails of the table in play without being jumped balls if they return to the bed of the table under their own power and without touching anything not a part of the table. 7. OPENING BREAK: At the start of each inning the player breaks from behind the headstring and has a free break (no special balls to cushion or other requirements once the break stroke commences, and there is no penalty for scratches or jumped balls). Also treble century, triple-century break, treble-century break. In the British Empire for most of the nineteenth through early twentieth century, pool referred specifically to the game of life pool. The generic term pocket billiards is sometimes also used, and favored by some pool-industry bodies, but is technically a broader classification, including games such as snooker, Russian pyramid, and kaisa, which are not referred to as pool games. Modern cue sticks are generally 58.5 inches (148.6 cm) long for pool while cues prior to 1980 were designed for straight pool and had an average length of 57.5 inches (146.1 cm). Of the many different pool games, the most popular include: eight-ball, blackball, nine-ball, ten-ball, seven-ball, straight pool, one-pocket, and bank pool.

British-style eight-ball pool, an originally British variant, also favoured in many Commonwealth countries, and parts of Continental Europe, with amateur and professional leagues. The British version of eight-ball, known internationally as either blackball or simply eight-ball, has evolved into a separate game, retaining significant elements of earlier pub versions of the game, with additional influences from English billiards and snooker. Many countries-among them France, England, China, Italy, and Spain-have been credited with the invention of the game, but, in fact, nothing is really known about the origin of billiards. The earliest rotation game, originally known as 61, started off as a variant of fifteen-ball pool during the mid-nineteenth century. By 1850 a variant called fifteen-ball pool became popular. 8.2. The player is entitled to any additional balls that are pocketed on a shot, as long as he pockets legally his called ball; the additional balls count the same as the called ball. On the other hand, Wanderone's public rival, Willie Mosconi, called one-pocket a gimmick game for gamblers. The earliest references to the game in Europe occur in the 15th century. It was the most popular billiards game in the mid-19th century until dethroned by the carom game straight rail.

These are games descended from the early 19th century games of pyramid pool and fifteen-ball pool which required balls to be racked due to the large number of them on the table. Cowboy pool and bottle pool are games involving only a few balls which are placed at specific spots on the table. 26. JUMP SHOTS. Unless otherwise stated in rules for a specific game it is legal to cause the cue ball to rise off the bed of the table by elevating the cue stick on the shot, and forcing the cue ball to rebound from the bed of the table. The OED defines it as generally "any of various types of billiards for two or more players" but goes on to note that the first specific meaning of "a game in which each player uses a cue ball of a distinctive colour to pocket the balls of the other player(s) in a certain order, the winner taking all the stakes submitted at the start of the contest" is now obsolete, and its other specific definitions are all for games that originate in the United States.