Generally speaking, the term authentication refers to any process of verification that someone, be it a human being or an automated system, is who (or what) it claims 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 it 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 ...