Abstract or Summary:
Nearly all websites that maintain user-specific accounts employ passwords to verify that a user attempting to access an account is, in fact, the account holder. However, websites must still be able to identify users who can't provide their correct password, as passwords might be lost, forgotten, or stolen. In this case, users will require a form of secondary authentication to prove that they are who they say they are and regain account access. Websites can use a variety of secondary authentication. The article discusses secondary authentication mechanisms, emphasizing the importance of assembling an arsenal of mechanisms that meet users' security and reliability needs.