Login Alerts and Two-Factor Authentication
Managing Your Alerts and Authentication Methods
Get alerts about unrecognized logins to Facebook
How two-factor authentication works on Facebook.
How do I use text messages (SMS) for two-factor authentication on Facebook?
Get security code for two-factor authentication to log into Facebook
Using an authentication app for two-factor authentication on Facebook
Setup Facebook login recovery codes
Fix a Problem With Two-Factor Authentication
Login alerts showing same device at every login
Log out of Facebook on another computer, phone, or tablet
Review recent Facebook logins
When & why to save your device to your Facebook account
I have to enter a security code every time I log into Facebook.