A welcome bonus, sometimes referred to as a sign-up bonus, is an incentive a casino offers to new customers when they join the site. Welcome bonuses typically involve the casino matching a percentage of a player's deposit. For example, if a casino offers a 100% match on deposits up to $100, a player who deposits $50 would receive an additional $50, doubling their deposited funds with bonus cash.
In most cases, welcome bonuses require players to meet minimum play-through requirements before they can withdraw any bonus funds or winnings derived from the bonus. These requirements vary from casino to casino, but generally, the more generous the bonus, the more stringent the requirements tend to be.