Fediverse refers to a network of federated, independent social networks, microblogging services and websites for online publication or data hosting. The concept emerged in 2008 with StatusNet on Identi.ca and from 2012 with GNU Social, and in 2016 it became increasingly widespread with Mastodon and the ActivityPub communication protocol defined by the World Wide Web Consortium (W3C) in 2018. People in the Fediverse call themselves “Fedizens”.
The idea of the “Fediverse” is that it should be possible to create a user account on any platform in the Fediverse and to be able to exchange information with users on all other platforms without having to create another account there. This is made possible by the fact that the individual platforms are connected to each other by means of certain communication protocols, thus distributing the federated identity and content to other connected platforms and entities. This practice is in contrast to closed social networks such as Twitter or Facebook, where users need their own user account on each of the networks if they want to interact with other users of the respective network.
The term “fediverse” was first used in connection with the OStatus protocol used by various social networks. In 2018, this was expanded to include services such as Mastodon, which use the ActivityPub protocol. In an expanded definition, networks such as Diaspora, which uses its own protocol, are also included in the Fediverse, as the instances are connected to other platforms that are part of the Fediverse. Sometimes, all decentralized networks that can serve as an alternative to networks such as Facebook or Twitter are referred to as Fediverse.
The lack of clarity in the exact definition brings with it some problems. For example, it cannot be assumed that all platforms in the Fediverse are actually compatible with each other in all functions and that content can be transferred from each platform to all others. This depends on the respective implementation and the protocol used. The only thing that all the individual platforms have in common is that they are decentralized, distributed social networks and free software.
The web platforms that make up the Fediverse are all free software. Some are similar to Twitter (for example, Mastodon or GNU Social, similar in their microblogging functionality and user interactions), while others offer more communication and transaction options that are then more comparable to Google+ or Facebook (such as Diaspora, Friendica, and Hubzilla). Part of the Fediverse are platforms that use communication protocols that connect multiple platforms in the Fediverse. Some use multiple protocols.
What is ActivityPub
Released in 2018, ActivityPub is an open, decentralized social networking protocol managed by the W3C. It offers a client-to-server API for creating, uploading, and deleting content, as well as a server-to-server API for decentralized communication.
ActivityPub is a standard for the Fediverse. The protocol used to be called “ActivityPump”, but the current name was a good way to emphasize the decentralized aspect of the protocol, according to various opinions. It bears some resemblance to previous protocols such as OStatus. In January 2018, the W3C released the ActivityPub standard and has since recommended it for decentralized content sharing.