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.
@ColinTheMathmo oh man I've done it again haven't I
Your chart is ready, and can be found here:
https://www.solipsys.co.uk/Chartodon/109546046424777715.svg
Things may have changed since I started compiling that, and some things may have been inaccessible.
In particular, the very nature of the fediverse means some toots may never have made it to my instance, in which case I can't see them, and can't include them.
The chart will eventually be deleted, so if you'd like to keep it, make sure you download a copy.