Two-factor authentication, also known as 2FA or TFA, is a two-step verification process that adds an extra layer of security in addition to a username and password. Sometimes the user will be asked for the answer to a security question. In other cases, the user will be sent an authentication code through an app like Google Authenticator. When you enable two-factor authentication, you should create backup codes immediately in case you lose your phone and cannot access the 2FA code.