CertiGuide to Security+  9  Chapter 1:  General Security Concepts (Domain 1.0; 30%)       9  1.2  Authentication

1.2.5  Tokens 1 1.2.7  Mutual Authentication

In the introduction we said something like, “a password or pass phrase is something you know. A device such as a smart card is something you have. Biometrics is something you are.”

Multifactor authentication involves the use of any two or more of these concepts together, requiring the user to furnish more than one type of proof of identity before access is granted. This greatly increases security, by reducing the odds that a lost smart card or accidentally disclosed password will give someone access to the network or system.

There is a high probability you use Multifactor authentication very often. The password (something you know) is weak; it is a mere 4 digits and numeric only. Yet most of us find that combining this incredibly weak password with something you have, to be sufficient security. If you haven't guessed yet, it is your ATM/Check Card/Debit Card.

1.2.5  Tokens 1 1.2.7  Mutual Authentication