Most of the bonuses offered online casinos are deposit bonuses. This means that the player first needs to make a deposit and he then gets a bonus which is specified as a percentage of the deposit. If the bonus is 100% of the deposit then the player depositing $100 will get a bonus of $100. If the bonus is 200% of the deposit then the player depositing $100 will get a bonus of $200. Most of the deposit bonuses have an upper limit. The bonus offer specifies what this upper limit is. Suppose the offer is 100% of the bonus subject to an upper limit of $200. A player who deposits $200 will get a bonus of $200, but a player who deposits $300 will not get a bonus of $300. 
His bonus will be restricted to $200.
So far the simple aspects of deposit bonuses have been explained. Most deposit bonuses are “play” bonuses. This would usually be mentioned in the bonus terms and conditions and not upfront in the promotions page. What this means is that the player cannot withdraw the bonus after he meets the wagering requirements. He is only entitled to the winnings from the bonus. The following example illustrates how this operates. Suppose the player avails of a 100% deposit bonus up to $100 by depositing $100. He will then have $200 to wager with. After completing the wagering requirements supposing he is left with $200. He cannot withdraw this entire amount. The moment the wagering requirements are complete the casino will remove the bonus amount from the player’s account and the player’s account will show only $100. Therefore the player can withdraw only $100. If the player had been left with $220 after completing wagering requirements, the bonus amount of $100 would be removed by the casino. The player would be allowed to withdraw his deposit of $100 and winnings of $20.
There is another condition that many online casinos apply on play bonuses, which is again embedded in the bonus terms and conditions or sometimes in the general terms and conditions. The online casinos put a cap on the winnings from bonuses that can be withdrawn by the player. In the above example suppose the cap on the winnings is $10. Then the player would not be allowed to withdraw the entire winnings of $20. He would be allowed to withdraw only $10 and the balance $10 would lapse along with the bonus.