Federated Learning of Cohorts (FLoC) was offered by Google as an earlier attempt to replace cookies. However, after releasing versions in its privacy sandbox, it didn’t pass privacy concerns, such as compliance with the EU’s General Data Protection Rules (GDPR). Google’s idea was to replace tracking cookies by creating cohorts of users with similar interests, such as intent to buy a car. However, privacy advocates demonstrated that such information could be used in combination with personally identifiable information to match individual users. So, Google opted not to proceed.