In recent decades, nine-ball has become the dominant tournament game in professional pool, in the World Pool-Billiard Association, Women's Professional Billiard Association and United States Professional Poolplayers Association. Matches proceed quickly, suitable for the time constraints of television coverage, and the fast-paced games tend to keep the audience engaged.
The game is played on a pocket billiards table with six pockets and with ten balls. The , which is usually a solid shade of white (but may be spotted in some tournaments), is struck to hit the lowest numbered ball on the table (often referred to as the ); each of these balls is distinctly colored and numbered 1 through 9. The object of the game is to legally pocket the 9-ball.
In nine-ball, except when a push-out has been invoked, a legal shot consists of striking the cue ball into the lowest numbered object ball on the table and subsequently either pocketing an object ball, or driving any ball (including the cue ball) to any rail, otherwise the shot is a . Additional conditions apply for the break shot (see below). Object balls do not have to be pocketed in numerical order; Any ball may be pocketed at any time during the game, so long as the lowest-numbered ball is contacted first by the cue ball. Nine-ball is not a game. The 9-ball itself can be legally pocketed for a win at any turn in the game, intentionally or by chance, including the break shot. Conversely, a player could potentially pocket all of the object balls numbered one through eight during the course of the game and lose after the other player pockets only the nine-ball.
Players alternate s at the table, meaning play continues by one player until he or she misses, commits a foul, or pockets the 9 ball for the win. The penalty for a foul is that the player's inning ends and the opponent comes to the table with , able to place the cue ball anywhere on the table prior to shooting.
Nine-ball is a relatively fast-paced game and is rarely played by the rack. Instead, players normally play a match (or ) to a set number of games, often five, seven or nine. The first player to win that set number of games wins the match.