MUCK or Multi-User Character Kingdom is a form of text based roleplay via the internet. There are other text based roleplays such as MUD (Multi User Dungeon), MUSH (Making fun of the other acronyms) and many other wonderful M words. It is in my own belief that MUCKs are the better of these worlds, MUDs being too cheesey and MUSHs granting little creative freedom (though in some cases it is needed). MUCKs are the medium between these two and is where I tend to stay. I have been on very bad mucks and very good mucks and if you'll read on, I can further enlighten you on this subject.
Want to MUCK?