FaceBook has been promising Secure Socket Layer (SSL) protection for a
while now. Well, it's finally here!
This is especially important when you are using open public wi-fi.
Your connection should be encrypted to keep prying eyes from
intercepting your information. Here's how to make sure you have this
basic precaution enabled when using FaceBook:

While on FaceBook, look at your URL; if you see http: instead of
https: then you don't have a secure session and your information can
be intercepted. To fix this, go to Account > Account Settings >
Account Security and click Change. Check both boxes to enable the
security provided by FaceBook. You MUST do this to enable these
security settings. FaceBooks default settings are INSECURE.