Mastodon is a free and open-source social networking service. It is similar to other social media platforms like Twitter and Facebook, but it is decentralized, which means that it is not controlled by a single company or organization. Instead, Mastodon is made up of a network of independently-operated servers, each of which is owned and managed by a different user or organization. This decentralized structure allows users to have more control over their data and their privacy, and it also makes the platform more resilient to censorship and other forms of control. Mastodon was created in 2016 and has since grown to have millions of users worldwide.