A MUX is basically the result of the evolution of MUD. On MUDs the main idea is usually to kill stuff. Most MUXes are more civilized than that.

There are different kinds of MUXes, depending on what purpose they are set up for. The main distinction is between RP and social MUXes.

• RP, or role-playing MUXes, are MUXes where you take on the role of a character in the world of the MUX, and are expected to stay in character except in certain OOC situations. However, most RP MUXes don't allow building and coding, and often have completely different sets of commands to use for RP. You will learn more about using RP MUXes by reading their own documentation than by reading this guide.
• Social MUXes are the type for which this guide is written. The object on social MUXes is to have fun and usually to contribute to building the world. There are non-themed social MUXes, such as ChaoticMUX, and themed social MUXes, like SluggyMUX.
• On a themed social MUX, you are not expected to act out the role of a character, but many players do have characters - either from the theme (like me, Squeeky-Bobo, one of the elves from Sluggy Freelance) or not (like Super Goth and Freaky Boy). Generally, on a themed social MUX, there is a public channel where players can converse from anywhere on the MUX. Other things are programmed objects ("code") that can be signs, games (often board games, but sometimes things of a larger scale), non-player characters (like Kiki on SluggyMUX), or contain useful commands for the MUX.

If you are reading this guide to use a MUX besides SluggyMUX (assuming this guide ever gets that popular), be sure to check your own game's rules. Some of what I'm saying here may not apply.