Two factor authentication is a form of multi-factor authentication that requires two distinct forms of identification before a user is granted access to something. Banks require an ATM card in addition to a specific pin before allowing customers access to their accounts at the ATM. Some websites also offer the option of using multi-factor authentication to log in and access your account. One of the most common forms of login via two factor authentication involves using a password and a code sent to a phone via SMS.
If you are concerned about your passwords ever being stolen or someone guessing what it is you can use two factor authentication as an added layer of security. This is especially important for banking and other financial sites where monetary damages can be caused by a malicious user with access to your account. You can find out if the service you use supports two factor authentication by checking this list. If the service you use supports two factor authentication you may have to activate it in the service’s settings.