These are General Rules that apply to all pool games, including Billiards, and Snooker. Exceptions to these general rules are noted in the Specific Games Pool Rules for each game.
Play By Innings
Players take turns at the table called innings. An inning continues until the player fails to pocket a ball on a valid shot, according to the rules for each game. The player at the table is referred to as the ‘shooter‘.
Rack is the number and arrangement of the object balls at the start of the game. Racks vary by game, but generally it is a triangle or diamond shape with the front ball on the foot spot.
A Break Shot is the shot that starts the game. Some games require the first shot of each rack to be an 'open break‘ in which at least four object balls make cushion contact. In matches that consist of several racks, the winner of each rack will break the following rack unless the rules for the game state otherwise.
A Called Shot means the object ball and the pocket as specified for the shot. Most games require the shooter to call the ball and pocket for any shot that isn't obvious. The usual convention is obvious straight-in shots are not explicitly called. Called shots do not require details such as kisses or combinations, only the ball and pocket.
Extra Balls Pocketed
For most games, If extra balls are pocketed on a shot, they usually count for the shooter.
Low Ball First
In a ‘low-ball-first‘ game (Nine Ball, Rotation, Ten Ball, etc.), the first ball the cue ball contacts must be the lowest numbered ball remaining on the table.
Cue ball-in-hand means the player can pick up and place the cue ball anywhere on the table. The break shot begins with ‘‘cue ball-in-hand behind the headstring, meaning that the shooter may place it anywhere in the top quarter of the table. Ball-in-hand also occurs after the cue ball is pocketed (scratched), hit off the table, and after other fouls in some games. Depending on the game, this may be either behind the headstring or anywhere on the table. The area behind the headstring is also referred to as the ‘Kitchen’.
When playing from behind the headstring, the first ball struck must be on the other side of the headstring. However, a ball behind the headstring may struck first if the cue ball crosses the headstring before contact, such as banking the cue ball off the foot rail. In case all legal target balls are behind the headstring, the one closest to the line is spotted so the shooter is not forced to play an out-and-back shot.
Most pool games spot balls in situations where a rules violation or illegally pocketed balls require balls to be returned to the table. They are usually placed on the foot spot, or as close to the foot spot as possible on a line between the spot and the center of the foot rail. If several balls are spotted, they are spotted in numerical order.
Some game penalize fouls by returning previously pocketed balls to the table. If the shooter fouls without any balls to his credit, he ‘owes‘ a ball to the table, and it is spotted at the end of the next inning in which he scores. Several balls may be owed.
In some games, other balls pocketed along with legal scoring balls are spotted at the end of the shooters turn. If the shooter pockets all balls on the table the delayed balls are spotted so the shooter can continue.
Fouls end a shooter's inning and are penalized according to the rules of each game. The following are fouls:
Scratch – Pocketed the cue ball
Ball Off Table - Hit a ball off the table. If a ball jumps onto the rail and returns to the table, there is no penalty
Bad Hit - In eight ball and the low ball first family of games, the cue ball contacts a non-target ball before a legal target ball. For all games, the cue ball does not contact a ball.
No Rail - If no ball is pocketed, and at least one ball does not contact a cushion after the cue ball contacts an object ball. This usually comes up during safety (defensive) play or when the shot is played too softly.
In some games, if one player fouls on three consecutive shots, there is an additional penalty, usually loss of the game. Games without a three foul rule may have a special rule to prevent stalemates.