In response to the post quoted below

“So what’s the deal with Mastodon anyway. Is it the prospective post-Twitter Musk-hater meeting place? Why would anyone choose to name their company after a prehistoric animal that humans hunted to extinction?”

The short and quick answer to that is that Mastodon is an open source program that provides Twitter like functionality. It's something that you can use to set up a social media website of your own.

It is possible for different instances of Mastodon to talk to each other but this highly depends on how the particular administrators have their instances configured and it is fairly common for instances to refuse to communicate with each other often for trivial reasons or just the administrator's personal preference.

So I would call Mastodon at best a semi-decentralized system because the general assumption of Mastodon is that most users will join an instance that's ran by someone else and that most users won't run their own instance. There is very limited portability of accounts between instances. Identity on Mastodon is completely tied to the individual instance.

It is possible to run your own instance just for you, and get some other instances to talk to your instance, but most people use other instances. The software isn't really built for one user instances, and generally assumes that an instance has a lot of users. Managing a Mastodon instance is relatively complicated compared to a lot of other server software.

The protocol that allows Mastodon instances to talk to each other kind of sort of resembles RSS but it's push based so an instance will notify other instances of new posts instead of pulling a list of posts from the instances. This results in a pretty different ecosystem because content tends to propagate from one instance to another and the usual configuration of a Mastodon instance is that it will mirror the content of the instances that it is connected to, and in some cases give users a feed of that content.

Mastodon instances usually have much heavier handed moderation than other social media.

Mastodon.social is probably the most popular Mastodon instance and when you hear people talk about Mastodon it or instances under similar management are what people are talking about.

Truth Social and Gab are also Mastodon instances, but probably aren't what people who talk about "Mastodon" mean. Most other Mastodon instances are very left-wing in their management.

My take on Mastodon is fairly negative. I think it's a system that somehow manages to reproduce kind of worst of Twitter but also has none of the benefits of true decentralization.

Most of what Mastodon is good at can be fundamentally done by other ways. My opinion on this type of thing is that the protocols of the old open blogosphere fundamentally worked. The reasons why the old blogosphere kind of died out are unrelated to the things that Mastodon is optimizing for.