system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does Facebook target-advertise the very product I just looked up in Google/other websites, despite me being logged out of my account at the time?

**It would be really helpful if you read the text below**

This has happened on numerous occasions, but now it's getting kind of disturbing. I deleted my account a while back, and created a new one for the sole purpose of joining my college's Facebook group in order to stay up to date with homework/exam dates etc. I literally have no one on my friends list nor do I have liked any pages with the said account. And here I am watching at my "Suggested Post" containing a product by SEO-MOZ (a website about SEO marketing), just after I looked them up (learned about them from Reddit), Downloaded their free PDF, and skimmed through some of their webpages. AND I was logged out of my Facebook account when I did that. How the heck?


**BTW,** this can not be a coincidence because as I said, it has happened before. I was once looking for a SPECIFIC protective case for Samsung Galaxy Note 4, called "Spigen Tough Armor" (logged out of my Facebook account as said above), which by no means is popular enough to be separately advertised on Facebook, and here it was, in "Suggested Posts"..

**EDIT:**yay! First time reaching the front page!
gpt
Some ads on Facebook are placed via Facebook Exchange, which allows advertisers who have compiled their own user data (via tracking cookies) to show ads on Facebook. 

For example, say you are on a computer that has never been logged into Facebook, and you go to nike.com. The site places a cookie on you, so anyone with visibility to that cookie knows you've been to nike.com. An advertiser can then go to Facebook Exchange and say "show a nike ad to any user with a nike.com cookie" without Facebook ever knowing you were on nike.com.