It is just simply a decentralized social network, you register and treat it like as if it is any other social network.
This guide from the people who run lemmy.ca is a good starting point.
a bunch of forums that talk to each other.
a decentralized collection of independently operated social media platforms that can choose to share information with each other.
Whenever anything is “federated” the easiest comparison is email. Everyone can use different email servers and applications, but they can all still communicate with each other. “Email” is the shared protocol that structures how data is exchanged between servers and clients.
The fediverse instead uses a protocol named “activitypub”, but works similar. Just a bunch of servers that speak the same technical language which enables them to freely exchange information. But while email only supports single messages, activitypub supports more complex structures that developers for platforms like lemmy or mastodon can use to make actual applications with an interface that gives you an easy way to display and structure that data like as a forum or blogging platform.
Email is a terrible example that people need to stop using.
ActivityPub literally uses inbox and outboxes just like email. Email is also widely adopted and understood. It’s the best analogy we have currently
