[chadnickbok]

You must supply a STUN/Turn server to the browser when setting up the connection, but if you're connecting to a public server you can use ICE-Lite implementations server-side to simplify the setup.

The ICE RFC does a good job of explaining it: https://tools.ietf.org/html/rfc5245#section-2.7

[pthatcherg]

You don't need to give a server. It works fine with just host ICE candidates from the server and no stun or relay candidates.