Mastodon, the social network, not the Heavy Metal Band, came on the social media scene just over 2 years ago. It was immediately embraced by those who felt Twitter had sold out to to corporate interests and wasn’t what it once was. It also seemed and still seems to not to be able to deal with its major troll issue.
Unlike the “birdsite,” as users of Mastodon call Twitter, Mastodon is completely open source and federated. This means that anyone can run their own “instance” or neighborhood on Mastodon and have it connect to the greater community. It’s really slick.
For example, there is Mastodon.Social that is run by developer(s) of Mastodon, but there are instances of the service for all types of communities.
I currently have more accounts on Mastodon than I remember, but the one that I use almost exclusively is Jawns.club, the Philadelphia (area) instance.
There are instances for techies, scholars, hipsters, witches, LGBTQ, etc. Mastodon is really democracizing the microblogging social networking arena.
Here is a great view explaining what exactly Mastodon is and why it rocks!