A mud or multi user dungeon is an environment that people from anywhere on the net can connect to any time of day or night. It's an excellent way to entertain, or to just share information with others. The difference between web pages and muds are many, but the primary difference is that muds are real time interactive. If there's 20 people online, all 20 can meet and discuss anything they like. Add to that the fact that a mud can be designed to be literally anything imaginable, and you have quite the environment for interaction or just plain fun.
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