This “You Should Know” post is top of ~June, for good reason. This post announced the kbin.social Federation/compatibility with Lemmy.
A huge amount of test-posts from a wide-variety of instances came in to test the new federation abilities (including from kbin.social, one of the biggest kbin communities).
I think this post shows the hope that over the long-term, we can get federation across the larger fediverse. I don’t know if Mastodon is in the works, but these kinds of posts give hope.
Federation is bilateral between servers. Whenever two servers interact with each other for the first time, a link is created between them. From then on they will inform each other about what is going on (unless they choose to break the connection). You post something in kbin, users can see it from Lemmy or Mastodon.
A federation is not an ideal metaphor, as federations tend to have a centralised authority. The fediverse is really a network of web sites that are all treated as equals, and all use the ActivityPub protocol. They need to find each other through user interaction: once they do, they are federated until either site chooses to “defederate” (as Beehaw famously decided with some servers).
The fediverse is this entire network of sites in the network: some have only created connections with a few other services, others are connected to the vast majority of services supporting the protocol. Over time, as users interact more, the network grows.