A sports book deposit bonus is a promotional offer provided by online betting platforms to attract new customers and reward existing ones. Typically, it involves matching a percentage of the player's initial deposit, allowing them to have extra funds to wager on their favorite sports. For example, a 100% deposit bonus up to $200 means that if a player deposits $200, they receive an additional $200 in bonus funds. These bonuses often come with specific wagering requirements, encouraging users to engage more with the platform before they can withdraw their winnings.