Security breaches on the Internet are in the news almost daily. It is becoming almost mandatory to enable 2-factor authentication on any site that requires a login.
Two-factor authentication is one of best things you can do to protect your online accounts from getting hacked. Two-factor authentication (2FA) also known as Two-step verification is a security process that requires the presentation of two authentication factors: a knowledge factor (something you know like a password) and a possession factor (something you have like your iPhone).
For example, if you have enabled Two-step verification with Google. When you log in to your Google account, you provide your login credentials, then Google will send you a code to enter to complete the login process.
Many major Internet sites support 2FA, but not all. To see what site support 2FA go to twofactorauth.org. There you will find a list of sites that support Two-factor authentication. If you favorite site doesn't, the twofactorauth.org provides a link to tell them to support 2FA.