The minimum required amount of chips that must be "bought" to become involved in a game (or tournament). For example, a $4-$8 fixed limit game might require a player to buy at least $40 worth of chips. This is typically far less than an average player would expect to play with for any amount of time, but large enough that the player can play a number of hands without buying more, so the game isn't slowed down by constant chip-buying.