Free spins are a common form of bonus, where a series of spins are automatically played at no charge at the player's current wager. Free spins are usually triggered via a scatter of at least three designated symbols (with the number of spins dependent on the number of symbols that land). Some games allow the free spins bonus to "retrigger", which adds additional spins on top of those already awarded. There is no theoretical limit to the number of free spins obtainable. Some games may have other features that can also trigger over the course of free spins.