GM (Game Master)

A Gamemaster or Game Master (often abbreviated as GM) is a player in a multiplayer game who acts as organizer, arbitrator, and officiant in rules situations.
Today, gamemaster is usually associated with role-playing games. In a role-playing game the Gamemaster's purpose is to weave the other participants' player-character stories together, control the non-player aspects of the game, and create environments in which the players can interact. The basic roles of Gamemasters - rules help, moderation, and storytelling - are the same in almost all role-playing games, although differing rulesets make the specific duties of the GM unique to that system.

Duties
The gamemaster prepares the game session for the players and the characters they play (known as player characters or PCs). The GM describes the events and decides on the outcomes of players' decisions. The gamemaster also keeps track of non-player characters (NPCs) and random encounters, as well as of the general state of the game world. The game session (or "adventure") can be metaphorically described as a play, in which the players are the lead actors, and the GM provides the stage, the scenery, the basic plot on which the improvisational script is built, as well as all the bit parts and supporting characters. Gamemasters can also be in charge of RPG board games making the events and setting challenges.

GMs 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 GM may build their own world and script their own adventures.

A good gamemaster draws the players into the adventure, making it enjoyable for everyone. Good gamemasters have quick minds, sharp wits, and rich imaginations. Gamemasters must also maintain game balance: hideously overpowered monsters or players are no fun. It was noted back in 1997 that those who favor their left-brain such as skilled code writers usually do not make it in the ethereal gamemaster world of storytelling and verse.[1]

Gamemasters in online games
A gamemaster's duties in an online game are less those of a gamemaster in a traditional role-playing game than a moderator or administrator in an online community. A GM in such a game is either an experienced volunteer player or an employee who enforces the game rules, banishing spammers, player killers and cheaters. For their task they use special characters with special abilities like teleporting to players, summoning items and browsing the player logs to help them in their moderating tasks. Gamemasters in MUDs are often called "wizards". Gamemasters in MMORPGs are usually employees of the game's host or developers of the game themselves, Ragnarok Online is an example of this type of GM. Often players who feel dissatisfied with the service will blame the GM directly for any errors or glitches. This is a common mistake as most employed GMs are not developers and cannot resolve the problem themselves.

The now defunct America Online Online Gaming Forum used to use volunteers selected by application from its user base. These people were simply referred to as OGFs by other members, and their screennames were indicative of their position (i.e., OGF Moose, etc.). While membership in the Online Gaming Forum had only one real requirement (that is, be a member of AOL), OGFs were given powers quite similar to AOL "Guides" and could call them in at will to ToS and/or ban users as they saw appropriate.

Note that a few games, notably Neverwinter Nights and Vampire: The Masquerade - Redemption, are computer game adaptations of tabletop RPGs that are played online with one player acting as a traditional gamemaster.

Gamemasters in online chats
Sometimes table top Gamemasters simply can not find players interested in either the same setting, product line, or play style in their local neighborhood. The advent of computers has brought a moderate solution to this in the form of online chat programs. This enables gamemasters to find players online, and for them to meet via chat rooms, forums, or other electronic means. This, in contrast to a normal table top game or a game meant to be played online, creates many more duties for a prospective gamemaster. It is wise to write out descriptive text ahead of time, and since the gamemaster cannot rely on his acting skills to get the personality of NPCs and monsters across, the need for music (often considered a distraction in a normal table top game) becomes much greater, as background music helps to set the mood for other players. The gamemaster must also keep hard copies of all the players' characters himself, since he can not glance at them as he would in a normal game. Moreover, the all players must rely on the honor system when determining the outcome of events through dice rolls, as the die is only visible to the player who most benefits from lying about it.

There are also some benefits. The use of Wiki software can allow Gamemasters to easily keep track of notes and characters that appear during play, as well as character sheets and other useful tools for the players. They may evolve into the equivalent of a home made gaming supplement. Scripting software allows complicated mechanics that include many tables or a lot of math to be resolved at a push of the button, while Teleconferencing allows the players and Gamemaster to communicate through voice, video, and a shared whiteboard. The use of technology to enable online play is growing, as can be seen from products like the DnD Insider.