As you can imagine, casinos that offer large bonuses have a higher chance of bagging new customers.Īfter bringing players on board with an online casino promotion, online gaming platforms need to actively retain them. Online casinos use such bonuses to stand out and compete for players. The best online casinos offer what are known as welcome offers to attract new players. They come in various forms, from cash to free spins. In simple terms, casino bonuses are deals offered by online casinos.