While gambling can be a lot of fun, it can also get hold of some people too tightly, and this is when problems can start to appear. Any decent online casino will promote responsible gambling, so you need to make sure that you sign up to one that does promote this just in case things start to get a bit too much for you and you find yourself playing more than you can afford.
Most legitimate online casinos will have a system in place where they can identify unusually high play, and also the ability to talk with a casino support team member and get your account locked down if you feel necessary. No casino should be encouraging you to play more if there is the slightest indication that you are playing beyond your means, so it is important that you find this out before you sign up.
Also, a casino should have support available to you on a 24/7 basis. You need to be able to talk to any member of their support at any time you like, and again this is now a pretty common thing with most good online casino sites. Support can usually be reached via a live chat system from inside your casino account, so it is very easy to access at any time you need it.
Responsible gambling is not just down to the casino though, it all starts with the player and it will require the player to know when they are playing more than they are financially capable of. The casino will just make it as easy as possible for a player to contact them, and also have trained staff that will know what to look out for if a player starts playing beyond their means. If you can be responsible enough yourself, then you should not ever need the casino to get involved, but it is always good to have that safety net there also.