Everything on Kbin and Lemmy is "federated"

This is basically just a fancy word to say "no matter what server you're on, we can all talk to each other".

It's kind of like E-Mail where no matter if you use GMail or Outlook, you can talk to your friends and colleagues.

When a server defederates from another server, It's like a two-way block.

People on (in this case) beehaw won't see threads, magazines and replies from Lemmy.world and sh.it just.works and people from Lemmy.world and sh.itjust.works won't see threads, magazines and replies from beehaw.org

Server/Instance admins usually do this when there are instances which spread unwished for content.

This is also why on my profile, there's a link (forum.fail). It's part of my identifier here on the Fediverse (@[email protected]).