Authentication

Authentication is a process in which the credentials provided are compared to those on file in a database of authorized users’ information on a local operating system or within an authentication server. If the credentials match, the process is completed and the user is granted authorization for access. The permissions and folders returned define both the environment the user sees and the way he can interact with it, including hours of access and other rights such as the amount of allocated storage space.

Authentication factors:

• Knowledge factors -- a category of authentication credentials consisting of information that the user possesses, such as a personal identification number (PIN), a user name, a password or the answer to a secret question.
• Possession factors -- a category of credentials based on items that the user has with them, typically a hardware device such as a security token or a mobile phone used in conjunction with a software token.
• Inference factors -- a category of user authentication credentials consisting of elements that are integral to the individual in question, in the form of bio metric data.

      http://searchsecurity.techtarget.com/definition/authentication