A GM, or Game Master, monitors MapleStory. They deal with user abuse(hacking, scamming, etc.) and host various events in the MapleStory world. Programmers are GMs as well but they are rarely seen, and usually participate in Server Checks. To determine a real GM, they have 'GM' flashing white and purple above their heads.
Dealing with Hackers and Scammers
As in every game, certain kinds of people like to ruin the game for others by scamming them (using certain keystrokes like Tab, Tab, Spacebar, Enter to confirm a trade without the user knowing), harrasing them ("u r ugly", "get a life u loser", etc.), hacking others accounts, and sometimes event hacking the MapleStory game itself. To prevent this, GMs implemented the 'Report Abuse' button on every Mapler's profile so if Maplers are doing something wrong, a user can report them. Rarely do they show up, however, because of all of the reports being sent in, and GMs cannot help every Mapler (see Criticsm below). Maplers usually get friends to report the user (usually when they use a 'Vac Hack' or a different kind of vac to unfairly get monsters to themselves), and if a GM still does not appear, users defame the hacking Mapler.
In the case that a GM does review the users actions, they will go to the Mapler and ask them to tell the GM about what happened. If the story seems okay, and if other users witnesed what happened/agree with the Mapler, the hacker will be blocked from the game.
In the case of a scamming, the user can report the other player, but this usually doesn't happen as the scamming Mapler will log out immediately after the scamming trade. But if they decide to run away instead of log out, the scamming Mapler has a small chance of being banned.
Soon after MapleGlobal_beta ended, Wizet decided to implement GameGuard into the game to prevent Maplers who attempt to hack the game. Very few fall to this, because they use a whole different program to hack the game (in which some programs are scams).
Every once in a while a GM will host an event to enhance Maplers enjoyment during the game. People will gather at the Event Start (usually in Lith Harbor, Orbis, or Southperry), and wait for a GM to appear. Once the event is about to begin, ingame popups will begin to appear counting down to the event start, in which you must talk to a NPC to get into the top 50,000 or so to play the event. For people who could not make the event, or are not in the top 50,000, a GM will usually cast a spell that only GMs may use to make the Maplers that could not get in the event in time feel better.
Many Maplers rant on how GMs are too lazy to do anything about hackers and scammers because they feel bad after they have been scammed, or because someone is using a Vac Hack to drag monsters to them. GMs respond and say that they are working as hard as they can to stop hackers and scammers from hurting the game or other Maplers, due to thousands of players reporting other players at the same time.