To preform the following actions, in loosely-coupled fashion, across #SocialMedia enclaves (or #DataSpaces) you need an open protocol (what #ActivityPub offers):
1. Create Posts (or Notes)
2. Follow Post (or Note) Authors
3. Like or UnLike a Post
4. Announce (or Boost) a Post
5. Delete Post
The collective arising from ActivityPub usage is the #Fediverse.
Mastodon has made the above both popular and broadly accepted.
@steve,
The @Mastodon and #Fediverse confusion is partly due to the fact that Mastodon only supports the Server-Server aspect of #ActivityPub while using its own #API for Client-Server interactions. Net effect, it has the lions share of clients generally perceived as Fediverse clients -- which is a strategic point of vulnerability over the longterm, IMHO.
/cc @tallship @Gargron @peepstein @blaine @atomicpoet