#ActivityPub is super cool once you see it in action.
For instance, you can visit the new StarTrek lemmy server here: https://startrek.website/c/startrek. Looks like a reddit sub with posts, threaded comments, upvotes, &c.
OR you can follow the same server on Mastodon @startrek.
Every thread and comment shows up as a boosted post.
Cool, right? Now, say you find a comment that you want to reply to. Post through your favorite Mastodon app, and that feeds right back to the thread on the #Lemmy server! 🤯
nothing. when that happens, you just move to another instance. or you run your own instance from the start. i guess in the future there will be tools to migrate complete community to another server. you have to give people time to develop them ;)
nothing. but running two different servers does not prevent running out of money, it only means you will run out of them twice as fast ;)
“instance” in one deployment of the lemmy software, one island in the sea, if you will. big instance can consist of multiple physical servers, but it is still the same instance, same version of the software run under the same domain, with same admins and so on. you as a user don’t know whether it is run on one physical server or whole rack and you don’t care - as long as the server doesn’t run out of resources.