The use of two independent mechanisms to verify the identity of a user, such as a password and smart card or a password and fingerprint scan. In these examples, people not only type in data but the smart card and fingerprint are unique physical objects that are difficult to duplicate. Text a Security Code Another method sites can employ is that after users log in with a password, a code is texted to their cellphone. Copying that security code from the phone into the login process provides the second authentication method. See authentication, smart card, password and one-time password.