In the context of a Content Management System (CMS), a user is simply someone who uses the site. If that were all there is to it, if everyone were always the same in the eyes of Drupal, we could stop right here. So, you won't be surprised to read that all users are not necessarily the same. Of course, I'm not referring to the personal aspects of the users when I write that; I mean that users are not necessarily all the same in terms of their reason for accessing the site and what ability they are given to do so.

If we look at USERS as a top-level classification with the thought of further classifying them, doing so depends on a choice: are we classifying them in a real-world sort of way, or as Drupal does? In the following table we see them compared: