What is Two Factor Authentication?

Two-factor Authentication adds an extra layer of security to your account. Once enabled, Sign-In will require you to enter a unique verification code generated by an app on your mobile device or sent via SMS text message or via email, in addition to your username and password. More detail of the Two Factor Authentication can be found on website Wikipedia:Simple_2FA

Step 1 : Login

Step 2 : Choose Authentication Methods

Verification codes will be sent to mobile phone.
Verification codes will be sent to registered email address.
Installation Help
This is a mobile application synced to your account which lets you generate codes to authenticate your sign-in.

Step 3 : Save Settings