Pinball is a type of arcade game, usually coin-operated, where a player attempts to score points by manipulating one or more metal balls on a playfield inside a glass-covered case called a pinball machine. The primary objective of the game is to score as many points as possible. Points are earned when the ball hits against one of many different objects in the machine such as a bumper or plunger. Near the lower bottom part of the playfield, there is a hole protected by plastic flappers. If the ball falls into the hole, that ball is out and the player starts with a new ball if he has more available. 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 free games (known as replays).