It is a common name for federated social networks running on free open software on a myriad of servers across the world. Historically, this term has included only microblogging platforms supporting a set of protocols called OStatus. This didn't do justice to a large number of projects that federate, share same values and are reasonably popular. With the appearance and wide adoption of a new standard protocol called ActivityPub it makes no sense to further divide the federated world into “OStatus” and “non-OStatus” projects. This guide unites all interconnected federated networks under one term “Fediverse”.