Trying to Understand Mastodon’s Federation

Mastodon is a decentralized, federated social network technology. With Twitter recently realizing its investor’s goals via an — unorthodox — sale to a wealthy entrepreneur and industrial scion with hard-right-leaning values, many people have wondered whether the platform will remain a useful or habitable place. Mastodon has been suggested as a possible Twitter replacement, and I’ve been trying to understand what, and more important where, Mastodon is.

These are some thinking out loud thoughts. If you’re a Mastodon expert and I’ve gotten something wrong please get in touch and let me know.

It’s like Email

One metaphor that’s emerged to explain Mastodon is email. I have an email address — foo@science.example.com. You have an email address — bar@magic.example.com. Our email is hosted on different servers, but we can still communicate with one another using an email program. Email is a federated technology.

Mastodon works similarly. I have a Mastodon address — @foo@science.example.com. You have a Mastodon address — @bar@magic.example.com. Our Mastodon content is hosted on separate servers, but we can still follow one another. We can still talk directly to one other or send direct messages. Mastodon is a federated technology.

On a 1:1 basis the email metaphor makes a lot of sense. However — Twitter is not just individuals following each other. It’s also the giant soup of watching everyone follow everyone else. While we all curate our feeds of individual people to follow there’s the wider world of global Twitter that leaks into our timelines and brings us things we might not expect. Sometimes for good, sometimes for ill. It’s an important part of the platform’s success and an important part of why people are there.

When we consider the global view, Mastodon’s federation starts to get a little more complicated and hard to understand.

Local Servers

When you use Mastodon you join a server — sort of like joining a message board or joining a slack/discord/IRC chat server. Servers are run by individual people or organizations. Some are general purpose, some are created with a special interest in mind.

When you’re logged into a Mastodon (via a client app or server’s website), your Home view is the people you’ve explicitly followed — both on this server, and other servers.

You’ll also have a view named Local. This is where you can see what people on this server are saying and tooting out. If folks are running the default Mastodon software the algorithm for this view appears to be pure chronological.

The Local view allows you to see what’s happening on this specific server.

Then, there’s a third view. The federated view — this is where Mastodon gets a little tricky.

Federated View

While every Mastodon server is a world unto itself, Mastodon servers also know about other Mastodon servers. We already talked a bit about this with person-to-person communication and following. In addition to this, Mastodon’s Federated view will display posts from every user in “the network”. Similar to the local view, this view is (or appears to be?) a chronological list of the most recent posts. “The network” is the list of other Mastodon servers that your server knows about. The Federated view is meant to replace the global Twitter view we talked about earlier.

The key to my understanding of the difference between Mastodon and Twitter is in the details of that federation. There are myriad ways a server knows about other servers — the underlying technical protocols of Mastodon take care of this. However, individual server administrators get to decide what servers their server federates with. I haven’t looked deeply at the implementation details but at a high level this can mean choosing to exclude individual servers, and it can also mean only federating with one or two different servers and creating a closed network.

This is a feature of Mastodon. Let’s say a group of violent right-wing extremists intent on hurting people and destabilizing the trustworthiness of the network show up with their own server. Administrators can just tell their own server not to federate with the nazi server, banning them from that server. It also means marginalized groups can create their own small networks of safer spaces to talk and share things.

The downside is Mastodon, or “the fediverse”, isn’t a concrete place. Instead, every Mastodon instance has its network of sites it knows about. These networks might overlap, but as a user, you’re placing a great deal of trust in the administrator of the server you join. They have a lot of power over what you see. They decide who gets to join your server. They decide which sites show up in federated view. If they chose to stop federating with a specific server, you will no longer be able to interact 1:1 with people from that server.

While every server (or, every server that’s running the default Mastodon software) has a list of moderated/blocked/banned sites on its about page (see mstdn.social for an example) it’s not always obvious when a server is removed from a network. Once you discover a favorite server is no longer listed you can always join another (and I think there are mechanisms to keep your followers and for your followers to keep following you, but I’m unsure) but it’s up to you to be on top of that. Participating in Mastodon is a much more active hobby than your bog standard social network.

Wrap Up

I wish Mastodon and the people of goodwill running it nothing but success. I might even join a server or two someday. That said, it’s a very different thing from Twitter. As much as people (and boy am I one of them) bemoan the internet we lost, the modern social networks like Facebook, Twitter, and Tumblr all managed to take the energy of the early social internet and create places where the entire world wanted to be and built systems that could handle the world’s interest. This required a tremendous amount of invisible work. Paid work.

Mastodon is a grand social experiment. I suspect we’ll see more small useful Mastodon communities crop up. However, the nature of the platform’s federation means it’s unlikely to be a place in the same way Twitter was and unlikely to capture the same sort of diverse global attention.