Pinball is a type of arcade game, in which points are scored by a player manipulating one or more metallic balls on a playfield 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 "storyline" 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. Different numbers of points are earned when the ball strikes different targets on the playfield. A drain is situated at the bottom of the playfield, partially protected by player-controlled paddles called flippers. A game ends after all the balls fall into the drain a certain number of times. Secondary objectives are to maximize the time spent playing (by earning "extra balls" and keeping the ball in play as long as possible) and to earn bonus credits by achieving a high enough score or through other means.