Social media sites like Facebook, Twitter and LinkedIn place trackers on other websites so they can follow what you do and see online. They do this to hit you with targeted, uncannily relevant ads. – Firefox
Firefox: Ever shop for something embarrassing only to have THAT thing show up in an ad following you across the internet? If so, you can thank a web tracker.
What we know about you when you click on this article – Vox
Online Trackers Follow Our Digital Shadow By ‘Fingerprinting’ Browsers, Devices
How to Reclaim Your Digital Privacy From Online Tracking – Lifehacker
I Visited 47 Sites. Hundreds of Trackers Followed Me. – NYT
Elsewhere on the Web
What are social media trackers
No Judgment Digital Definitions: What is a web tracker?
No judgment digital definitions
Tracking Diaries with Matt Navarra
Online Tracking – FTC
Our favorite free social web sites are not really free — we are paying with our data.