Two-factor authentication on Facebook

Facebook also supports two-factor authentication (which it calls Log in Approvals). Facebook’s two-factor authentication process is activated whenever you log in from a new computer. An SMS is sent to your phone containing a unique security code, which you will need to enter into Facebook before you can log in.

Set it up using following the instructions on https://www.facebook.com/ help/ 148233965247823/ [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]