Open up developer tools and look at the network requests just about any website you visit makes. Logged in to facebook.com and then went to visit a.com? Well, a.com has a Facebook like button and script delivered to your browser when you load their page that allows Facebook to figure out that your logged in Facebook user id visited a.com. Not only did you do that, but you hovered over a button to buy boots for 3 seconds and didn’t click. Now, Facebook calls home with the knowledge user 827027 is a potential boot buyer and can spam them with boot ads.
Interestingly, a.com also loads about 30 other scripts from other ad networks and trackers, including Google, and similarly lets them call home with info stored in their respective third party cookies.
Open up developer tools and look at the network requests just about any website you visit makes. Logged in to facebook.com and then went to visit a.com? Well, a.com has a Facebook like button and script delivered to your browser when you load their page that allows Facebook to figure out that your logged in Facebook user id visited a.com. Not only did you do that, but you hovered over a button to buy boots for 3 seconds and didn’t click. Now, Facebook calls home with the knowledge user 827027 is a potential boot buyer and can spam them with boot ads.
Interestingly, a.com also loads about 30 other scripts from other ad networks and trackers, including Google, and similarly lets them call home with info stored in their respective third party cookies.