“every time i gotta explain the instances i'm like why”
– Nameless Rumia

The “Fediverse” (federated(interconnected) universe) is meant to be a distributed social network, tied together by instances/servers that anyone can run, except most people don't really care and just wish to sign up for the most popular ones without understanding the point of decentralization.

Most platforms tend to rely on a centralized server, while decentralization lets anybody establish their own instance with no single overarching authority. However, this means that each instance is run by different teams that may decide to hide/limit and block/suspend other instances, which is why it's important for users to do their own research and assess the policies, leanings, and tolerance levels¹⁾ of each instance.

Regardless of what instance you choose, you should be able to interact with other instances through an “all” or “global” tab of some sort. This means that, if you can't join a popular instance or the same one as your friends, you should be able to communicate with that instance regardless. If you can't, again, do keep in mind that some may hide or block other instances at their discretion.

It's easy to mistake the Fediverse as an alternative to Reddit or Twitter, but the Fediverse actually has many different forms which are usually FOSS. The server owner, at their discretion, may choose to set up: microblogging, macroblogging, a news aggregator, image sharing, video sharing, etc. Below is a small handful of notable software packages that you may have possibly heard of at some point.

Early attempts at populating the Fediverse were sparse in the early 2010s as Diaspora came²⁾³⁾ and went.⁴⁾ Then in February 2016, rumors of an algorithmic timeline on Twitter⁵⁾ caused “#RIPTwitter” to trend,⁶⁾⁷⁾⁸⁾ encouraging migrations to GNU/Social instances like Quitter.⁹⁾ However, the rumors were quashed,¹⁰⁾ so the migration stalled and some people started to blame moderation styles.

GNU/Social was quickly supplanted by alternatives like Mastodon or Pleoroma. However, it wouldn't see any new waves of users until the Twitter acquisition in November 2022, where “#RIPTwitter” would trend once more^11)12)13) with Mastodon as one alternative.¹⁴⁾¹⁵⁾ In the following months, Reddit saw a massive protest in June 2023 which saw a handful of communities attempt a migration towards Lemmy or Kbin.¹⁶⁾¹⁷⁾

• In other words, the Fediverse is somewhat reminiscent of P2P distribution.
• Some people have started to shorten Fediverse to “Fedi”, but this hasn't exactly taken off yet.
• Donald Trump's Truth Social platform was revealed to be a Mastodon fork.¹⁸⁾¹⁹⁾

• Fediverse.party - An overview of the main Fediverse platforms.
• Fediverse.observer - The alternate, complex overview. I don't suggest the closest server.
• Fediverse on Wikipedia