Many online casinos offer sign-up bonuses to new players making their first deposit, and often on subsequent play as well. These bonuses are a form of marketing that may incur a cost (potentially justifiable in order to attract a new player who may return and deposit many more times), since the casino is essentially giving away money in return for a commitment from the player to wager a certain minimum amount before they are allowed to withdraw. Since all casino games have a house edge, the wagering requirements ensure that the player cannot simply walk away with the casino’s money immediately after claiming the bonus. These wagering requirements are commonly set to be sufficiently high that the player has a negative expectation, exactly as if they had deposited and not claimed a bonus.
Casinos may choose to restrict certain games from fulfilling the wagering requirements, either to restrict players from playing low-edge games or to restrict ‘risk-free’ play (betting for instance both red and black on roulette), thereby completing the wagering requirement with a guaranteed profit after the bonus is taken into account