Tracking Protection for 
Firefox
Start your adventure with about:config
Turn on browser.polaris.enabled
This turns on tracking protection
The shield means Firefox is protecting you
Click it for the lowdown
Disable protection per-site if you want
Or re-enable it, if you change your mind
Report bugs to trackingprotection.info
Some addons may interfere with tracking protection
Thanks for testing! #stoptrackingwithfirefox

How to turn on Tracking Protection for Firefox