Modern ad tracking is really horrible. Consumer Reports looked at the state of things when it comes to Facebook, and determined that each user is monitored by thousands of companies. Gross.
I use Facebook approximately never, but I figured I’d check on this myself, following the “How Can You See Your Data?” directions in the linked article. I found several dozen connections from the past year or so, all of which I disconnected, for whatever tiny good that might do me.

