Pocket billiards, also called Pool, a billiards game, most popular in the United States and Canada, played with a white cue ball and 15 consecutively numbered coloured balls on a rectangular table with six pockets (one at each corner and one at the midpoints of both longer sides). The dimensions of the table are usually 4 by 8 feet (122 by 244 cm) or 4 1/2 by 9 feet (137 by 274 cm).
To begin play, the 15 object balls are arranged (racked) in a pyramid formation with its apex on a spot near the foot of the table. The first player then stands at the head of the table and drives the cue ball into the formation to break it apart. To continue play, he is usually required either to pocket a ball or to drive two object balls in addition to the cue ball against the cushions. When a player fails to pocket a ball, his opponent begins play. The first player or side to pocket eight balls wins the round.
After the break (first) shot, a player must designate (call) the ball that he intends to pocket, although in this form of the game he need not indicate the pocket into which the ball will go. If the ball called is pocketed, any other balls pocketed on that stroke are also credited to the player. If the ball called is not pocketed, any other balls pocketed on that shot are replaced on the table on the spot where the rack is made or, if more than one ball is replaced, in a line from that spot; the player then loses his turn.