Jump/break cue.

Break

One person is chosen to shoot first, using a cue stick to break the object-ball rack apart. If the shooter who breaks fails to make a legal break (usually defined as at least four balls hitting cushions or an object ball being pocketed), then the opponent can call for a re-rack and become the breaker, or elect to play from the current position of the balls.

According to World Standardized Rules, if the 8 ball is pocketed on the break without fouling, the breaker may ask for a re-rack and break again, or have the 8 ball spotted and continue shooting with the balls as they lie. If the breaker scratches (pockets the cue ball) while pocketing the 8 ball on the break, the incoming player may call for a re-rack and break, or have the 8 ball spotted and begin shooting with ball-in-hand behind the head string, with the balls as they lie. (For regional amateur variations, such as pocketing the 8 on the break being an instant win or loss, see "Informal rule variations", below.)

Turns

A player (or team) will continue to shoot until committing a foul, or failing to legally pocket an object ball on a non-foul shot (whether intentionally or not). Thereupon it is the turn of the opposing player(s). Play alternates in this manner for the remainder of the game. Following a foul, the incoming player has ball-in-hand anywhere on the table, unless the foul occurred on the break shot, as noted previously.

Selection of the target group

At some point in the game, one of the players can select (or is assigned) balls 1–7 (the "solids") or balls 9-15 (the "stripes") as their group of object balls. The other player is assigned to the other group. Once the target groups have been assigned, they remain fixed throughout the remainder of the game.

Pocketing the 8 ball

Once all of a player's or team's group of object balls are pocketed, they may attempt to sink the 8 ball. To win, the player (or team) must first designate which pocket they plan to sink the 8 ball into and then successfully pot the 8 ball in that called pocket. If the 8 ball falls into any pocket other than the one designated or is knocked off the table, or a foul (see below) occurs and the 8 ball is pocketed, this results in loss of game. Otherwise, the shooter's turn is simply over, including when a foul such as a scratch occurs on an unsuccessful attempt to pocket the 8 ball. In short, a World Standardized Rules game of eight-ball, like a game of nine-ball, is not over until the "money ball" is no longer on the table. This rule is unusual to some bar and league players, because in American, Canadian and many other varieties of bar pool, and in some leagues, such as APA, such a foul is a loss of game. This is not the case in World Standardized Rules, nor in some other leagues that use those rules or a variant of them, e.g. VNEA beginning with the 2008/2009 season, and BCAPL), and USAPL.

Winning

Any of the following results in a game win:

A player legally pockets the 8 ball into a designated pocket, after all of that player's object balls have been pocketed

The opposing player illegally pockets the 8 ball (e.g. before clearing all of that player's object balls, does so on the same shot as the last such object ball, or the 8 falls into a pocket other than the one that was designated)

The opposing player knocks the 8 ball off the table.

The opposing player commits any foul, including scratching the cue ball into a pocket, or knocking it off the table, in the course of a shot that pockets the 8 ball. (As noted above, a scratch or other foul while shooting for the 8 ball is not a loss of the game if the 8 is not pocketed or jumped from the table.)

Fouls

1) The shooter fails to strike one of his own object balls (or the 8 ball, if all of said object balls are already pocketed) with the cue ball, before other balls (if any) are contacted by the cue ball. This excludes "split" shots, where the cue ball strikes one of the shooter's and one of the opponent's object ball simultaneously.

2) No ball comes into contact with a cushion or is pocketed, after legal cue ball contact with the (first) object ball (or 8 ball, if shooting for the 8).

3) If an attempt is made to pocket a ball, and the ball hits the pocket, bounces out and lands out off the table on the ground, the ball is placed in the pocket and the game continues.

4) The shooter does not have at least one foot on the floor (this requirement may be waived if the shooter is disabled in a relevant way, or the venue has not provided a mechanical bridge)

5) The cue ball is shot before all balls have come to a complete stop from the previous shot

6) The cue ball is struck more than once during a shot

7) The cue ball is jumped entirely or partially over an obstructing ball with an illegal jump shot that scoops under the cue ball

8) The cue ball is clearly pushed (shoved slowly, rather than struck), with the cue tip remaining in contact with it more than momentarily

9) The shooter touches the cue ball with something other than the tip of the cue

10) The shooter touches any ball (with body, clothing or equipment), other than as necessary to move the cue ball when the player has ball-in-hand

11) The shooter knocks a ball off the table

12) The shooter has shot out-of-turn

13) On the break shot, no balls are pocketed and fewer than four balls reach the cushions (in which case the incoming player can demand a re-rack and take the break or force the original breaker to re-break, or may take ball-in-hand behind the head string and shoot the balls as they lie)