Bank pool

Bank pool is a pool (pocket billiards) game that has as its most fundamental requirement that all scoring shots in the game must be made by banking a called ball off a cushion and into a called pocket. While the game has multiple variations, the predominant version through much of its history was played with a full fifteen-ball rack, of which the winning player was required to legally pocket eight balls. A shortened version of the game using nine balls of which the players must legally pocket five for the win, often called "nine-ball banks," gained popularity in the 1990s and 2000s and is the subject of international professional competition and televised matches.

The object of the game is to be the first player to bank five balls in any order (or eight balls, when played with a full rack).

The balls are racked in nine-ball formation (or eight-ball formation if using a full rack), but in no particular order.

On the break shot, at least four balls must hit the rails else it is an illegal break. Any balls pocketed during the break do not count toward the score and will be spotted after the player's inning ends. Pocketing a ball on the break results in the player continuing to shoot.

On an illegal break, the opponent has the option of requesting a re-rack or accepting the table as-is and may begin shooting.

The key rule is that all shots must be banked (cue ball to object ball, then object ball to one or more cushions on the way to the pocket).

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Wikipedia