A deposit bonus in the UK is a promotional offer provided by online casinos and betting sites to attract new players and retain existing ones. Typically, it involves matching a percentage of the player's initial deposit, allowing them to play with extra funds. For example, a 100% deposit bonus on a £100 deposit gives players an additional £100 to wager. These bonuses often come with specific terms and conditions, including wagering requirements, which players must meet before withdrawing any winnings. Overall, deposit bonuses enhance the gaming experience by providing more opportunities to win.