It is its own community that happens to be federated with Lemmy and Mastodon. You can toggle federation on and off, and when off, you only see kbin's material. Otherwise it functionally acts like another lemmy instance, with a different interface and features missing from base lemmy.
There is also a microblog attached to it that connects with Mastodon in the same way. Each community has its own microblog that acts as a hashtag when on Mastodon.
And Lemmy, they all talk to each other via ActivityPub. There's a number of commenters in this thread that are commenting from Mastodon and Kbin (like yourself) while I'm on Lemmy.
It is its own community that happens to be federated with Lemmy and Mastodon. You can toggle federation on and off, and when off, you only see kbin's material. Otherwise it functionally acts like another lemmy instance, with a different interface and features missing from base lemmy.
There is also a microblog attached to it that connects with Mastodon in the same way. Each community has its own microblog that acts as a hashtag when on Mastodon.
i'm pretty sure when federation is off it also means you won't see other kbin instances, just your own
This I didn't know. So posting a comment on the microblog will make it visible to Mastodon as well?
And Lemmy, they all talk to each other via ActivityPub. There's a number of commenters in this thread that are commenting from Mastodon and Kbin (like yourself) while I'm on Lemmy.
Lemmy isn't designed to access microblogs or follow individual users though, so you'd probably never see it from Lemmy.
This is where I link my own post from a few days ago - but basically to say kbin is actually a very good way to browse Mastodon "Toots", and yes you can post just as easily too.
https://kbin.social/m/fediverse/t/275724/Browsing-the-wider-fediverse-from-kbin