https://motherboard.vice.com/en_us/article/wj7nzw/firefox-browser-to-block-facebook-data

In the wake of the Facebook data scandal, many users are only now realizing just how insidious the social network’s data-collection techniques are. Facebook is collecting information on its users even when they’re not on the site itself, which is why Mozilla has introduced a new browser plugin for Firefox that blocks Facebook from doing just that.

“There’s enormous value in tying this data to your social profile, and Facebook has a network of trackers on various websites,” Mozilla wrote in a blog post about the new plugin. “This code tracks you invisibly and it is often impossible to determine when this data is being shared.”