Identification, Authentication and Authorization

Identification occurs when a user claims their identity,

authentication occurs when a user proves their identity,

authorization occurs when correct identification and authentication have been done and a user needs access to resources for which he has specific permissions which are otherwise restricted for unauthenticated users.

Example, in an ID card: ID number provides identification; using the ID card with password to log in to the employee portal provides authentication; and finally, using the ID card (which, lets say belongs to the data center admin) to get access to the data center's server rack provides authorization since that permission is only with the DC admin.