FLoC

Federated Learning of Cohorts (FLoC) is a technology created by Google that uses an algorithm to track users as they browse the internet. This tracking happens directly in the web browser without any need for cookies or javascript running on individual websites. The way it works is that Chrome will monitor your browsing history and then place you into a "flock" or group of similar people who share certain characteristics. It then discloses this group ID to individual websites that request it so that they can display more targeted advertising.

If a website wants to opt-out of being used in the FLoC calculation it can add this value to the Permissions-Policy HTTP header. This header protects the privacy of the users of the website.

Permissions-Policy: interest-cohort=()

This test will check to see if FLoC has been disabled for the website and report a warning if it isn't.

For more information, please read Google's description on web.dev and to learn more about security and other headers which can benefit your users, please read our article on Security Headers.