TinyMUCK or, more broadly, a MUCK, is a type of user-extendable online text-based role-playing game, designed for role playing and social interaction. Backronyms like "Multi-User Chat/Created/Computer/Character/Carnal Kingdom" and "Multi-User Construction Kit" are sometimes cited, but are not the actual origin of the term; "muck" is simply a play on the term MUD.