I want to host a TURN server for my WebRTC project, but I don't know what the 'realm' attribute does. I've looked at coturn and pion and they both seem to require me to enter this. Can someone explain what it is?
It is a "key" to access a group of address that have a common "owner". It is an isolating measure: a TURN server can have one "default realms" or more "named realms" in its database. And any realm has its own users and each of them have a proper login/password couple to identify access and working sessions. Of course, computers which made a login into a "named realm" are virtually "invisible" to other which belongs to other realm. If you simply log in the "default realm" where all users use same login/passwd ( tipically with "public" TURN servers ) your machine can be reached by all computers in a easy way also from unkown machines for this reason the "realm" was a useful thing to have
... and that is all .. :)