Known this for years and I wish I could find the original thread here on FR that discussed it some 10+ years ago now.
Briefly:
1. Do a fresh OS install of Win7/8/10 or Linux on any computer.
2. Browse Yahoo.com, Amazon.com, eBay.com, NY Times, and pick any other ten top twenty websites you want. Exception: DO NOT BROWSE FACEBOOK.
3. Go examine the cookies on the computer. You'll find you're being tracked by Facebook without ever having browsed Facebook on that computer or opened a facebook account with that computer.
So many websites, online shopping sites, etc.. send their cookie data to Facebook for correlation. In summary, your browsing information is correlated to your computer and your identity for marketing purposes. It's a HUGE part of Facebook's revenue stream.
You and I cannot possibly opt out of all the advertising services/cookies that are set on our computers that are sent to facebook.
What we CAN do is BLOCK FACEBOOK from setting cookies on our computers. I do that. Ther are video's on how to do it, all one has to do is LOOK.
Want to kill Facebook? Learn to block their cookies and stop them from correlating your data.
Educate yourselves, people. You're being tracked by them even if you don't have an account there.
Beware ‘persistent cookies,” and other insidious methods. Trackers imbedded in a single pixel in an image—for real.
Me: No Script, Ghostery, Privacy Badger addons on firefox, with privacy settings set quite high. And PIA VPN, set to “always on.”
There are sites you can go to that “inspect” your computer over the net, see how invisible and annonymous you are. Kind of a targeted attempt to hack in and invade privacy. I score completely invisoble, and never get targeted ads.
Getting tougher. Now they “fingerprint” your browser, look at every transmitted setting (resolution, etc.), try to identify you that way.