Mastodon is an open source federated microblogging service/social media platform. A federated social network is decentralized, similar to how email works. Since Mastodon is open source, anyone with enough technical know-how can create their own Mastodon server where users can register. A Mastodon server is comparable to the email provider in the email system. Mastodon servers can communicate with each other via a standardized and open protocol called ActivityPub. Thanks to this protocol it is possible that users from one Mastodon server can for example follow users from other server or like their content.