The welcome offer is the biggest draw for new players. For new accounts, the casino signup bonus is usually a 100% deposit match up to a certain amount — usually, up to $500–$1000. So, if you deposit $100, the casino site will throw in an extra $100 of credits plus a bunch of bonus spins on select games.
Still, before you opt in for any such offer, you’ll want to consider the wagering requirements. If you have a 40x condition and only a few days to play through, it might be difficult (or impossible) to actually meet those requirements and get to the withdrawal stage. On top of that, most welcome bonuses are tied to slot games. That means if you’re a roulette, poker, or blackjack fan, it makes little sense to accept the offer.