MUD stands for Multi-User Dungeon (Dungeon being a single-player text adventure; it was the predecessor of the widely-famous Zork). MUDs are accessed through a telnet client, although raw telnet is very hard to use in a MUD, since it receives information only if you send some - so you may have to press the Enter key a lot in order to keep up with what's going on.

You can move your character around the world, which is constructed of rooms - text descriptions of a place. They are not necessarily all rooms inside - most MUDs have enormous wilderness areas. You can manipulate objects - things that are lying around, such as weapons, food, fountains, or backpacks. And you can interact with creatures, also known as non-player characters or "mobs" (short for "mobile"). Most interaction with creatures is either killing it or buying things from it, if it's a shopkeeper. Some of them may give you quests. How each MUD uses these three basic elements is up to the implementer(s) of that MUD.

Of course, being a multi-user environment, there are other players, too, each basically doing what you are doing. You can interact with them through speech, socials (preset commands in the MUD to do things like smile, laugh, frown, dance, etc.) or emotes (a manual sort of social - typing "emote flaps his wings and covers everyone in faerie dust." would send a message like "Mish flaps his wings and covers everyone in faerie dust.") Some may be open to going off to adventure with you, or trading with you. And you can even kill another player (or be killed by another player) in a PK - a player kill.

Behind the scenes, doing the hard work and fighting the good fight, are the immortals, or imms for short. Some MUDs may use a different name, such as wizard, ancient, or even god, but in the end, they are all the same. The immortals influence the world in many different ways, falling into one or more of the following categories:

Coders determine how the world works. They create the races, classes, skills, spells, and general "physics" of the MUD's world, including what a player can or can not do. On a large MUD with several coders, their efforts will be led by a head coder, who watches what the others do, and checks their code for soundness.

Builders determine how the world looks. They are responsible for practically every single creature, room, and object in the game world (coders may create such things for spells, but those are stored in a special area file). Most building teams are coordinated by a head builder, who is, in the end, responsible for smooth flow, continuity and balance in the world.

Administrators, also known as admins, deal with the day-to-day operations of the MUD. They are responsible for things such as keeping the helpfiles up-to-date, dealing with problem players, making sure immortals are working well together, and hiring new immortals, if need be.

Implementers, also known as imps are responsible for putting everything in the game - both code and areas. More often than not, both the head coder and head builder are imps.

Enforcers simply enforce the rules. This becomes important on larger MUDs, where the other immortals are generally too busy doing their primary jobs to enforce rules all the time. However, on smaller MUDs, most every immortal is an enforcer.

Questers (or questmasters, or the generic questing imm run quests to entertain and challenge players. Often, on a MUD with OLC, they will be assisted by a builder to create rewards and creatures. An example of a simple quest is to kill a dragon who is attacking the countryside.

Webmasters simply maintain the MUD's website and its forum(s). Usually, a MUD's website contains such basic information as what classes, races and clans are playable, a general overview of its areas, and a list of its rules and laws. Sometimes they may have a listing of who is on the MUD, or a list of its skills and spells. It's quite rare that an immortal won't have knowledge of HTML, or access to a WYSIWYG editor, but in that event, an outside webmaster will be used. Otherwise, the webmaster will be a member of the MUD's current staff.

Owners, as the name implies, own the MUD (well, they own the server space the MUD occupies). They pay the bills for the server. It's extremely rare that the owner won't take an active part in his or her MUD - usually at the head builder or coder level.

Keep in mind that most immortals will fall into more than one of these categories - at one time, I was a head builder, an administrator, and an implementer. That can be a lot of work for one person to handle ^.^ Primarily, however, I was a builder. I've completed 19 areas for ROM 2.4, several of which will never be available for download, because they're my babies ^.^