In a role-playing game, the game master (or dungeon master, more common among people who play Dungeons and Dragons) is the storyteller. He or she prepares the adventure for the players, describes the events, and decides on the outcomes of players' decisions. The game master also keeps track of non-player characters and random encounters.
A good gamemaster draws the players into the adventure, making it enjoyable for everyone. Good gamemasters must also maintain balance - hideously overpowered monsters or players are no fun!
Good gamemasters have quick minds, sharp wits, and rich imaginations.
Also known as: dungeon master, storyteller, referee (or "ref") in Cyberpunk