Secure Communication
Nov 4, 2026 • 10 min read
How Matrix Federation Works, and What Every Homeserver in a Room Stores
Every Matrix homeserver with a user in a room keeps a full, signed copy of that room. End-to-end encryption hides message content from all of them, but senders, timestamps, membership, reactions, reply links and room names stay readable. How joins, backfill and state resolution work, what each server stores, and what that means for retention, erasure and moderation.
S
Sri Pranav Tene 
