A 100% deposit bonus is a promotional offer commonly used by online casinos and sportsbooks to attract new players. When a player makes their first deposit, the casino matches the amount, effectively doubling the player's initial funds. For example, if a player deposits $100, they receive an additional $100 in bonus funds, giving them a total of $200 to play with. This bonus enhances the gaming experience, allowing players to explore more games and increase their chances of winning. However, it's essential to read the terms and conditions, as wagering requirements may apply before cashing out any winnings.