Log into your Facebook account via computer and select Account at the top right corner.

Then select

• Account Settings
• Scroll down to Account Security
• Check the box called ‘Login Approvals'
• Click the "Login Notifications" checkbox to you are notified of account changes

This security feature seems a bit tedious to some, and if you may find the process a bit exhausting if you access Facebook from multiple locations. However, if you are having issues with keeping your account secure the added steps and security may be worth the extra hassle.  To get the direct description of how this feature works – check out the post from Andrew Song on Facebook.

Thanks to Abbi Siler for posting this @ http://local2social.com/2011/facebook-login-approvals/