Pretty much every online casino offers a Welcome Bonus to all of their new players that sign up with them. This is a great marketing tool used by the casinos as it draws plenty of new players through their virtual front doors. But it is also very beneficial to you as the player, as it will give you the chance to play at the casino on their money, and you can also play a lot of the games too.
Not all Welcome Bonuses are alike, in fact they vary quite significantly. But one things that many people do not know is that you can keep money that you win while using the initial casino bonus. Now there are lots of terms in place for this, and they will differ from casino to casino, so you should always check this out first.
It is highly unlikely that any casino will allow you to hit a progressive jackpot and keep all the money while playing on the casino bonus, but certainly if you win a few hundred dollars or so then you will be able to cash that out as regular money in your account. You will probably have to reach certain play-through amounts first though.
The best thing to do is to look for a blog that lists all of the best online casinos that are currently available, and then choose which one you think offers the best Welcome Bonus.