Federated learning of cohorts (FLoC) is a privacy-oriented technique for targeting online advertising that is being developed by Google. FLoC is an alternative to traditional tracking methods, such as third-party cookies, that rely on the collection and sharing of personal data. Instead, FLoC uses machine learning algorithms to group users into cohorts based on their interests and behavior, and to target ads to these groups, rather than to individual users. FLoC is designed to provide advertisers with the ability to target ads effectively, while also protecting the privacy of users, as it does not require the collection or sharing of personal data. FLoC is still in the development and testing phase, and it is not yet clear whether it will be widely adopted by the advertising industry.