A 300% deposit bonus is an enticing promotional offer often used by online casinos and betting sites to attract new players. When a player makes a deposit, the site triples the amount, providing extra funds to explore games or place bets. For example, a $100 deposit would yield an additional $300 in bonus money, giving players a total of $400 to play with. However, it's essential to read the terms and conditions, as these bonuses typically come with wagering requirements that must be met before any winnings can be withdrawn.