Among the bonuses offered in online casinos there are, for example, reload bonuses and refer-a-friend bonuses. There’s also the cash back bonus, which is the rarest. The reason for that is other bonuses generally mean that the player will do more wagering, while the cash back bonus refers to past wagering and usually doesn’t require any future actions other than playing according to requirements.
A cash back bonus compensates a percentage (usually 10-15%) of how much a player lost in a specific period of time, with an upper limit. The players who won don’t need the bonus because they’re already happy with their winnings. If the players who lost are compensated even a little bit, they’re most likely to keep playing.
In some online casinos cash back bonuses are weekly, which means that they money compensated is the maximum of the bonus or the percentage of losses (whichever is lower) at the end of the week. In other casinos the bonus might apply to a specific day of the week or to a particular game or type of games. There are also casinos that only provide cash back bonuses in special promotions.