The fediverse (commonly shortened to fedi)[1][2][3] is a collection of social networking services that can communicate with each other (formally known as federation) using a common protocol. Users of different websites can send and receive status updates, multimediafiles and other data across the network. The term fediverse is a portmanteau of "federation" and "universe".[4]
The majority of fediverse platforms are free and open-source software, and create connections between servers using the ActivityPub protocol. Some software still supports older federation protocols as well, such as OStatus, the Diaspora protocol and Zot. Diaspora* is the only actively developed software project classified under the original definition of fediverse that doesn't support ActivityPub.[5][6]