One could write books about Mastodon and the Fediverse (which of course has been done), so the information here is really the super high level explanation what they are all about.
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.
Simply put, it puts the control of data into the user's hands, not in a single corporation. Mastodon is just one of many platforms on the Fediverse.
The Fediverse is a network of interconnected servers, which communicate with each other based on decentralized networking protocols, primarily ActivityPub. These servers can be used for any number of different services, such as social media or file hosting. Some examples of popular services are Mastodon, Peertube (video hosting, like YouTube), and Pixelfed (photo sharing, like Instagram). These services can interact with each other, so you can follow Pixelfed accounts from your Mastodon accounts, for example.
ActivityPub is a decentralized social networking protocol based on the ActivityStreams 2.0 data format. ActivityPub is an official W3C recommended standard published by the W3C Social Web Working Group. It provides a client to server API for creating, updating and deleting content, as well as a federated server to server API for delivering notifications and subscribing to content.
There are a lot of sites which have an immense amount of information on Mastodon and the Fediverse. Below you can find some of them. Check them out!
Because of the open nature of the Fediverse, the community has come up with some wonderful tools to make use of and extend the software provided. Below are some of those tools.