American Ten-Pin Bowling's Rules
Each game, or line, of bowling, consists of ten turns or frames. In each frame, the player rolls two balls to try to knock down 10 pins.
If the player cannot knock down all the ten pins in the two tries, this is calles an open frame. The score for the frame is the total number of pins knocked down in the two tries.
If the player knocks all the pins down in two tries, this is called a spare frame and the score for the frame is ten plus the number of pins knocked down on the next throw in his next turn.
If the player knocks down all the pins on his first try in the frame, this is called a strike frame. His turn is over, and the score for the frame is ten plus the total of the pins knocked down in his next two rolls.
If the player gets a spare or strike in the last frame, he is allowed to throw one extra ball. No more than three balls can be rolled in tenth frame. The game score is the total of all frame scores.
Note: the gutter is a trench on each side of the lane; if the ball falls into the gutter, it scores zero: this called a gutter ball.
