Defederation
When a Fediverse instance breaks all federation with another — users on the two servers can no longer see or interact with each other. The central moderation tool for handling problem instances without a global authority.
How: an admin blocks an entire domain → no traffic passes in either direction. Used against instances with spam, harassment, extremism, or illegal content. Two levels: "limit/silence" (softer — content shows only if you actively follow) and "suspend/block" (full break). Federation is a voluntary relationship, not a right → each instance decides for itself who it associates with. Controversial for large actors: the FediPact campaign was about preemptively defederating Threads. Trade-off: protects the community but fragments the network and can hurt innocent users on a blocked instance. FediBlock lists share recommendations among admins.