So here's how I understand it:
lemmy.world, lemmy.fmhy.ml, beehaw, (instances) etc. are all basically different servers. But they essentially all have access to the same communities, aka the equivalent of a subreddit, even though some communities are are hosted on lemmy vs beehaw, etc.?
If my understanding is correct, then, for the layman, each different instance can be seen as a site to view any of the communities, so we can register with one instance, and browse everything they all have to offer. Is that about right? Sorry, I know a guide has been posted, but I'm trying to reduce the functionality to fit into my feeble mind.