Free deposit bonus codes are promotional offers provided by online casinos and betting sites to attract new players and retain existing ones. These codes allow users to receive additional funds or free spins when they make a deposit, enhancing their gaming experience without significant financial risk. Players can enter these codes during the deposit process to unlock bonuses, which can be used on various games. However, it's essential to read the terms and conditions, as wagering requirements and expiration dates may apply, ensuring players understand how to maximize their benefits.