It‘s like Twitter basically, but since it‘s also in the fediverse there is a bit of overlap where Mastodon people can comment on Lemmy/kbin stuff too anyway. Usually they have something like @LostCause and hashtags like #mastodon and so on in their comments, that‘s how I typically spot them.
So their growth is relevant for us, but you don‘t need to make an account there.
Thank you, this makes sense. Can I view Mastodon posts from lemmy.world? I can’t recall seeing any but maybe it’s not obvious.
If a mastodon user mentions (@) a community, they’ll post there. They can also reply to comments on Lemmy and you’ll see it. Unfortunately I don’t think Lemmy has a way to see regular mastodon accounts/comments right now other than that.