Even if nobody is standing in the beam there is still at least air.

If you host your own, do you need to establish federation with all other instances or only with the ones you want to use communities from?

If I only federate with lemmy.world, would I be able to see comments on /c/selfhosted@lemmy.world on my instance made by a user from lemmy.ml?

Would a user that reads /c/selfhosted@lemmy.world on lemmy.ml see my comments, if I only federate with lemmy.world?