Since its launch in October 2016, microblogging social network Mastodon has been gaining ground, reaching 1 million users as of December 2017. To many it's the anti-Twitter. Though much like it in appearance and feature-set, Mastodon places greater emphasis on safety and privacy.

Decent article written before Lemmy (when diasopra was the apparent alternative). Still worth reading, especially for those new to the fediverse concept.