The vast majority of slot games will have some form of free spins bonus rounds included. The exact way this is triggered depends on the game, but it is usually a case of landing 3 or more designated scatter symbols. Once the bonus is triggered, the free spins can be played without your real cash or bonus cash balance being used. Once the free spins round is over, the winnings are added up and paid into your balance. In some slots, it is possible to retrigger or extend the free spins round by landing special symbols on the reels.