https://www.theregister.co.uk/2019/12/03/eff_web_surveillance/

As the sacred shopping season gets underway, the Electronic Frontier Foundation has issued a report detailing the privacy cost of surveillance-based commerce.

Issued on the Monday after the US observance of Thanksgiving, a day so known for online shopping that marketers branded the event with its own commerce-promoting moniker, "Behind the One-Way Mirror" explores the technology of corporate data gathering, specifically third-party tracking. That's when websites and applications include code that enables entities other than the website or app publisher to gather data about those interacting with the software.