I get this question a lot from various people, so it deserves its own post. Here's how to turn on Tracking Protection in Firefox to avoid connecting to known tracking domains from Disconnect's blocklist:
- Visit about:config and turn on privacy.trackingprotection.enabled. Because this works Firefox 35 or later, this is my favorite method. In Firefox 37 and later, it also works on Fennec.
- On Fennec Nightly, visit Settings > Privacy and select the checkbox "Tracking Protection".
- Install Lightbeam and toggle the "Tracking Protection" button in the top-right corner. Check out the difference in visiting only 2 sites with Tracking Protection on and off!
- On Firefox Nightly, visit about:config and turn on browser.polaris.enabled. This will enable privacy.trackingprotection.enabled and also show the checkbox for it in about:preferences#privacy, similar to the Fennec screenshot above. Because this only works in Nightly and also requires visiting about:config, it's my least favorite option.
- Do any of the above and sign into Firefox Sync. Tracking Protection will be enabled on all of your desktop profiles!