Concept
Mastodon is free and open-source software for running self-hosted social networking services. It has microblogging features similar to Twitter, which are offered by a large number of independently run nodes, known as instances, each with its own code of conduct, terms of service, privacy policy, privacy options, and content moderation policies. Each user is a member of a specific Mastodon instance (also called a server), which can interoperate as a federated social network, allowing users on different instances to interact with each other. This is intended to give users the flexibility to select a node whose policies they prefer, but keep access to a larger social network. Mastodon is also part of the Fediverse ensemble of computer servers, which use shared protocols allowing users to interact with other users on computers running compatible software packages such as PeerTube, Friendica, and Lemmy. Mastodon is crowdfunded and does not contain ads. Mastodon was created by Eugen Rochko and announced on Hacker News in October 2016, and gained significant adoption in 2022 in the wake of Twitter's acquisition by Elon Musk. The project is maintained by German non-profit Mastodon gGmbH. Mastodon servers run social networking software that is capable of communicating using W3C's ActivityPub standard, which has been implemented since version 1.6. A Mastodon user can therefore interact with users on any other server in the Fediverse that supports ActivityPub. Since version 2.9.0 Mastodon has offered a single column mode for new users by default. In advanced mode Mastodon approximates the microblogging user experience of TweetDeck. Users post short-form status messages, historically known as "toots", for others to see. On a standard Mastodon instance, these messages can include up to 500 text-based characters, greater than Twitter's 280 character limit. Some instances support even longer messages. Users join a specific Mastodon server, rather than a single centralized website or application.