If you're wanting a simple quick way to explain how Mastodon works, there's an official animation from a few years ago which goes over the general principles. Here's a copy of it someone uploaded to the Fediverse:

https://tilvids.com/w/hRzMpJwSkqEK3ZTNPbSuqu

The original video is on YouTube if you prefer that:

https://www.youtube.com/watch?v=IPSbNdBmWKE

The principles explained in the video also apply to the whole Fediverse that Mastodon is part of: many servers talking to each other to form a single network.

#Mastodon