Two-factor authentication (2FA) is an extra layer of security added to your account. It is also known as "multi-factor authentication" or "two-step verification."
2FA not only requires a username and password but also a time-based, one-time password (also known as "OTP") that only you have access to through your phone.
The OTP is generated by an app on your phone based on your secret key (that we generate for you) and the current time. An OTP can only be used once and is only valid for a short period.
In a nutshell, to access your account, you (or anyone else) need your username, password, and your mobile phone to get the OTP.
Download Authy App
The Authy app, once setup, will generate One-Time Passwords when you need them. There are other apps available (just search for "2-factor authentication" in your app store), but Authy can backup up your codes in case you lose your phone.