Do you find Mastodon confusing? So did I! Basically... if you're a gamer, you can think of Mastodon like an MMO, with multiple servers hosting its own population of players, all playing the same game at the same time. You can also think of it like email. <userXYZ>@hotmail.com can interact with anyone else that as an email address.

To get started, you find a server to join and sign up there. From then on, you will be known as <userXYZ> from Federated Server<ABC>.