It all depends on whether the online casino adheres to Know Your Customer regulations. Not all online customers will have to carry them out, so for these online casinos you won’t need to provide any documentation to identify yourself. However, it should be noted that these online casinos aren’t always the most trustworthy sites and unless there is a solid reason why it doesn’t use Know Your Customer protocols, then you should be wary about playing there. For example the Malta based casinos, that are seen as most trusted, HAVE to know who is playing.
For sites that do use Know Your Customer regulations then you will often need to provide some identification documents in order to make deposits and withdrawals at the site. This will usually be some form of photographic identification. Something along the lines of a driving license or passport is usually required. This is to ensure that players are truly who they say they are and make sure that players aren’t carrying out fraud by using someone else’s bank details.