A high-roller bonus is a type of enticing offer given to players who make a large deposit at an online casino. High-rollers are players who deposit more money than average, usually in the area of hundreds or thousands of dollars.
The offer of a high-roller bonus is a reward offered to these VIP players, to incentivize them to continue making large deposits. Casinos benefit by having the advantage of offering large amounts of money in exchange for loyalty.
The specific bonus varies by casino, but typically is marked by a percentage of the player's deposit that will be rewarded in bonus funds from the casino, offering the player a greater chance of winning, as well as other perks.