In the Dungeons & Dragons (D&D) role-playing game, the Dungeon Master (abbreviated as DM) is a selected participant who describes the game to the other players. In effect, the Dungeon Master creates the entire world and allows the players (the DM is usually not described as a player) to interact with that world.
The title was invented for the TSR Dungeons & Dragons RPG, and was introduced in the second supplement to the game rules (Blackmoor). To avoid infringement of TSR's copyrights, and to describe referees in role-playing genres other than swords and sorcery, other gaming companies use more generic terms, like Game Master, Referee, or Storyteller.
Role of the Dungeon Master Edit
The Dungeon Master (DM) presides over each D&D game session, serving as both storyteller and referee. As such, he/she is responsible for preparing each game session, and must have a thorough understanding of the game rules. Since the inception of the Advanced Dungeons & Dragons system in 1977, these rules have been contained in three hardbound books: the Player's Handbook, Dungeon Master's Guide and Monster Manual. Many other rulebooks exist as well, but these are not required for conducting the game.
In storyteller role, the DM describes the events of the D&D game session and makes decisions about the course of a game session based on the decisions made by the players. As described in the main article on Dungeons & Dragons, each player generates a fictional player character (PC) who plays within the game session. The DM develops the plot and setting in which these PCs participate. The DM keeps track of non-player characters (NPCs), as well as random encounters with monsters that antagonize the PCs. The DM is also responsible for developing the game campaign and the game world.
Another aspect of dungeon mastering is that the DM is not required to follow the rules per se. Indeed, he/she has the authority to modify or even remove rules that might not fit into his/her game. This license, however, comes with great responsibility. The game system as published is generally regarded as balanced; the DM must ensure that any changes he/she makes maintains such balance. Unless the players do something that has no rules, or is not talked about in the DMG. An example would be if the PCs are attacked by a living statue. To destroy the enemy, one PC soaks the statue in water, while the second uses his cone of cold breath to freeze the water. At this point, he appeals to the DM, saying the water expands as it freezes and shatters the statue. The DM can allow it, or roll 'probability' (a ten sided die and a probability die). In the above example, the probability roll might came up in favor of the players, and the enemy would be shattered.
The game session is typically known as an "adventure". It can be metaphorically described as an act within stage play, where the players are the lead actors. In this analogy, the DM provides the stage, the scenery, and the basic plot on which the improvisational script is built, as well as all the bit parts and supporting characters.
A series of adventures generally compose a campaign. Using the stage play analogy, a campaign would comprise all acts of said play. While each adventure may have its own story arc, they are usually parts of the larger story arc of the campaign. The DM strings individual adventures into this campaign, in which the same PCs fight many different monsters and a few recurring villains; the PCs gain treasure, reputation and power as they go. Such campaigns can last for years or decades, earning a great deal of loyalty from their players. Also, there can be a common theme (e. g., find the Sword of Light) to a number of adventures that may in time become a campaign of sorts.
Beyond the campaign is the "game world". This vast construct is typical of many fantasy novels, such as J.R.R. Tolkien's Middle-earth or Robert E. Howard's Conan saga. DMs may choose to run a game based on a published game world, with the maps and history already in place; such game worlds often have pre-written adventures. Alternately, the DM may build their own world and script their own adventures.
DMs may run their game as frequently as they wish; some gamers meet weekly or monthly, while others may only meet two or three times a year. A DM can also run a single adventure otherwise unconnected with a campaign or game world. In this latter case there is no connected plot, and the players can choose to play different characters in each session.
Also, in Faiths and Pantheons (AD&D), the Faerunian Overgod Ao answers to a superior entity, insinuated to be the "Dungeon Master".da:Dungeon Master el:Dungeon Master es:Dungeon Master fr:Dungeon Master he:שליט המבוך zh:DM