Start9 on Nostr: If you choose to federate your server (it is a setting in Config), then you will be ...

If you choose to federate your server (it is a setting in Config), then you will be able to join rooms on other [Tor] servers, and [Tor] users will be able to join rooms on your server, if it's a public room or you invite them, that is.

This link seemed useful, but there is a ton of stuff online explaining what federation means and how it works: https://teknikaldomain.me/post/matrix-decentralized-federated-chat/