Online Threat Alerts (OTA) - Alerting you to scams and frauds.
Useful - Informative
You can improve the security of your Facebook account by getting an alert when someone tries logging in from a device or web browser we don't recognize. These alerts will tell you which device tried logging in and where it's located.
To get alerts about unrecognized logins:
After you start getting alerts about unrecognized logins: