authenticationVerifying the identity of a user. is the process of a user confirming that they are who they say they are on a computer system. In a network, this is often done through inputting a username and password. For networks that require high levels of security, authentication may include other methods.
The factors of authentication can be broken down into three main groups:
something you are - username, bank account number, or anything that identifies the user uniquely
something you know - password, pin, secret answer to a question
something you have - swipe card, biometrics, any other physical identifying device