With most sites these days, regardless of their purpose, you need to know who your users are. You might need to know this so that you can restrict where the users go on your site. Or you might need this information so that you can provide a dynamic experience to your user. No matter what your reason is to know who your users are, the task of identifying and controlling them has a few basic requirements.

In order to get to know our users, we will need a way to register them on our site. This would give us a footprint for that user, which we can use each time the user returns. The registration process is fairly straightforward most of the time. We need to capture the data that we are interested in (such as username, password, email, and so on). We need to make sure that we store their password properly so that their identification is safe not only from the other users of the site but also from the administrators and staff of the site. Also, given the amount of fraud and spam on the...