A kind observation that exclusively calling this place "Mastodon" has a bit similar energy as saying "I just sent a GMail."
"Fediverse" (or "fedi") is a more inclusive, general term.
Mastodon is just one of many software projects that talk to each other to create this multi-instance social network:
https://axbom.com/fediverse/
(kudos to @axbom for this fantastic infographic!)
There are blogs, Reddit-like communities, video instances and many more, all part of fedi.
@rysiek @axbom I use #StarTrek to explain it: #Fediverse is the Federation of aligned worlds.
#Mastodon is Earth, #Misskey is Vulcan, #Pixelfed is Centauri Prime & #Pleroma is Bajor.
There are many worlds & each server is like a starship or space station from that world.
#ActivityPub is the universal translator that connects them all.
#Twitter is the Klingon Empire, while #Facebook is the Borg.