<self-satire>
I think you'll find that the correct term is GNU/Mastodon, or GNU+Mastodon.
Many fediverse users run a modified version of GNU social every day, without realizing it. Through a peculiar turn of events, the version of GNU social which is widely used today is often called “Mastodon,” and many of its users are not aware that it is based on the protocol of GNU social, developed by the GNU Project.
</self-satire>
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<self-satire> (cont/d)
There really is a Mastodon, and these people are using it, but the whole system is basically GNU social with Mastodon added, or GNU/Mastodon.
Many users do not understand the difference between the app, which is Mastodon, and the whole fediverse, which they also call “Mastodon.” The ambiguous use of the name doesn't help people understand. These users often think that Eugen Rochko developed the whole fediverse in 2016, with a bit of help.
</self-satire>
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I don’t know whether to be pleased or embarrassed that my 2017 'brief history of the fediverse' blog piece continues to get linked here every now and then, and in blog posts about the fediverse. Despite the fact that the only way to do that is via archived copies. Because the service that hosted my blog vanished from the web in 2020, not with a bang, but with a whimper.
To make it easier to find, I've posted a copy on SocialHub: