Dungeon Master — One of the people sitting around the table for your Dungeons & Dragons (or some other) game usually takes on a role known as the Dungeon Master or the Game Master. Sometimes this person is simply called The Referee, the Game Master (GM), or the Storyteller. This Dungeon Master describes the world, the conditions, the complications — she interprets the world for the player-characters. The Dungeon Master adjudicates situations that arise in the unfolding story where two or more outcomes are possible — often using various dice to help with these decisions. You may also want to read here.