I'm one of the people who has very recently tried Lemmy and decided to drop Reddit. Initially because I will no longer be able to use SyncForReddit, but now also because I just like the vibe a lot more here than Reddit.
I'm not a massively technical person, but I understood the broad concept of federation - different instances/servers that sync to form a big conversation/forum of sorts.
I heard a lot of people joining and saying positive things about lemmy.world, so I signed up there.....and that's it.
But, am I using it right? Is the idea to sign up in one place and use it to participate across the LemmyVerse/FediVerse? Or should I be seeking out lots of niche instances of interest?
I hear lemmy.world is the biggest instance. What if most people end up here, does that defeat the purpose? Is this inevitable?
You need a critical mass of users, so a quiet instance with few posts is not attractive. If I search for Xbox, there are lots of empty places or places with 3 posts. If there's one big one (often ends up being in lemmy.world) that's where I'm subscribing.
How are you using Lemmy, are you participating in a bunch of instances or just one?
So you have an account at Lemmy.world. From Lemmy.world you can subscribe, post and comment in communities on ANY Lemmy or Kbin instance (except Beehaw, for reasons).
So suppose you want to subscribe to a magazine* over at Kbin.social. You can just go ahead and subscribe to it from your Lemmy.world account and it will just work and show up in your 'subscribed' feed (and you'll be able to make posts and comments there). That's what this 'federation' thing means.
In other words, since all the instances are federated, you can see and interact with content from across the federation right on your 'home' instance.
(In fact, that's the difference between the 'local' and 'all' tabs on the homepage – 'local' is just content from that instance, while 'all' is content from across the federation.)
* 'magazine' is the Kbin term for 'community', which is equivalent to a 'subreddit'