It is a normal thing for people to be able to get some money for credits on the gambling sites where you play online. Due to most of them trying to get peoples attention they will have big ads for ways to get money. They do push the purchase bonuses the most but many still do give free money without having to deposit.
These are real casinos with real payouts not just fly by night operations that just want to take money without ever having to pay. Those casinos which use to exist are gone now, as that can only last for so long before word spreads. Now you have proper casinos that want players happy and want them long term. The amount of money you get depends on the type of promotion it is. Some will give bonuses up to 1600 with purchase that is added to your overall funds and others give a percentage so the more you deposit the more you get. The free offers are not to much as they just want to give you a sample into there world not break their bank. So if you play a bit and have some luck it is all good but if you want to get serious you will probably continue to play, deposit some money and see if you can hit one of those really decent wins that so many others have. Money offers will come along monthly from many of these sites as they try to keep you active they will reward you with certain bonuses normally starting at the first of the month and may continue on or be offered towards the middle and end of the month. It is also common to see them run some sort of contest that players win based on play, not all will win but the top ones get a pretty decent size bonus. To check the offers you just log into your account now and then to see what’s up and opt to engage in the deal if you happen to like what they have given.