Authentication and Authorization
Generally speaking, the term authentication refers to any process of verification that determines whether someone, be it a human being or an automated system, is who (or what) they claim to be. This is also true within the context of the World Wide Web (WWW), where that same word is mostly used to denote any technique used by a website or service to collect a set of login information from a user agent, typically a web browser, and authenticate them using a membership and/or identity service.
Authentication should never be confused with authorization, as this is a different process and is in charge of a very different task. To give a quick definition, we can say that the purpose of authorization is to confirm that the requesting user is allowed to have access to the action they want to perform. In other words, while authentication is about who they are, authorization is about what they’re allowed to do.
To better understand the difference...