One of the more tedious moments in visiting a new website is filling out the registration form. Here at Domain of the Cube Forum, you do not have to fill out a registration form if you are already a member of Drupal. This capability is called distributed authentication, and is unique to Drupal, the software which powers Domain of the Cube Forum.
Distributed authentication enables a new user to input a username and password into the login box, and immediately be recognized, even if that user never registered at Domain of the Cube Forum. This works because Drupal knows how to communicate with external registration databases. For example, lets say that new user 'Joe' is already a registered member of Delphi Forums. Drupal informs Joe on registration and login screens that he may login with his Delphi ID instead of registering with Domain of the Cube Forum. Joe likes that idea, and logs in with a username of firstname.lastname@example.org and his usual Delphi password. Drupal then contacts the remote.delphiforums.com server behind the scenes (usually using XML-RPC, HTTP POST, or SOAP) and asks: "Is the password for user Joe correct?". If Delphi replies yes, then we create a new Domain of the Cube Forum account for Joe and log him into it. Joe may keep on logging into Domain of the Cube Forum in the same manner, and he will always be logged into the same account.
Drupal is the name of the software which powers Domain of the Cube Forum. There are Drupal web sites all over the world, and many of them share their registration databases so that users may freely login to any Drupal site using a single Drupal ID.
So please feel free to login to your account here at Domain of the Cube Forum with a username from another Drupal site. The format of a Drupal ID is similar to an email address: username@server. An example of a valid Drupal ID is email@example.com.