MUD (/ˈmʌd/; 原指 Multi-User Dungeon 多用户迷宫，后又被称为 Multi-User Dimension 多用户空间与 Multi-User Domain 多用户领土)_，台湾用户通常直接称呼为MUD。通常将缩写字直译为「网络泥巴」或是简称「泥巴」(英文 mud 的意思为泥巴)。是一款多人即时的虚拟世界，通常以文本描述为基础。 MUD 结合了角色扮演、砍杀、玩家与玩家对战、交互小说与在线聊天等元素，玩家可以阅读或查看房间、物品、其他玩家、非玩家角色的描述，并在虚拟世界中做特定动作。 玩家通常会透过输入类似自然语言的指令来与虚拟世界中的其他玩家交互。

A MUD (/ˈmʌd/; originally Multi-User Dungeon, with later variants Multi-User Dimension and Multi-User Domain), is a multiplayer real-time virtual world, usually text-based. MUDs combine elements of role-playing games, hack and slash, player versus player, interactive fiction, and online chat. Players can read or view descriptions of rooms, objects, other players, non-player characters, and actions performed in the virtual world. Players typically interact with each other and the world by typing commands that resemble a natural language.