Authentication is the process of verifying the identity of something or someone, often for security purposes, through some unique characteristic. Although the term has a specific meaning in the context of computer use, authentication is something people do on a regular basis. An object may be identified to an expert as an "authentic" antique by its manufacturer's mark or signature. An individual will be "authenticated" to family and friends by face recognition, or in the case of speaking, voice recognition. So for instance, in a telephone call to a friend, the caller is granted access to information that the call recipient regards as appropriate based on the recipient's recognition of the caller's voice. This is a basic form of authentication. In the computer world, authentication is the process by which a user (a person or a device) is granted access to a computer, a...