GoldSpark is asking what the little Halo Ring icon is on the Halo PC Server Lobby; it is shown in the picture below circled in red:
Gold, what that ring icon is used for is to show players which servers use default game types, and which servers use edited game types. So, if a server has a ring icon displayed, that means that the server is using a default game type. If a server does not have a ring icon displayed, then the server's game type has been edited.
A§H»Spyker's post in Server browser window explanation was marked as the answer