Pinball is a type of arcade game, usually coin-operated, in which points are scored by a player manipulating one or more steel balls on a play field inside a glass-covered cabinet called a pinball machine. The primary objective of the game is to score as many points as possible. Many modern pinball machines include a story line where the player must complete certain objectives in a certain fashion to complete the story, usually earning high scores for different methods of completing the game. Points are earned when the ball strikes different targets on the play field. A drain is situated at the bottom of the play field, partially protected by player-controlled plastic bats called flippers. A game ends after all the balls fall into the drain.