(go over this to check the facts!)
The acronym MOO stands for Multi-user dungeon, Object Oriented. That may not leave you any teh wiser, so let me explain it properly. A MOO is a place on the netpeople can talk together, build things and worlds together, play games and learn and discuss things. MOOs are descended from MUDs (Multi-User Dungeons) which are descended from those text-based adventure games a lot of people played in the late seventies and the eighties before computer games were so graphical. In the early eighties, some people made an adventure game that people could play together, using networked computers. This kind of game became known as a MUD. Soon there were lots of different kinds of MUD: some were mainly social places where people chatted with each other, others were game-oriented, and people chose roles to play and solved quests of various kinds.
A MOO is a kind of MUD that uses an object-oriented programming language. You don't need to know what that means to find MOOs enjoyable or useful. The first, largest and most famous MOO is LambdaMOO and LambdaMOO is still an interesting place to visit. LambdaMOO is a social MOO, where people chat and play and build and program odd objects. As the Internet became more and more accessible, especially in universities, people started to use MOOs for education as well as for fun. Today there are many educational MOOs, which are used both in on-campus and distance education. If you'd like to visit some, there's a good overview of educational MOOs at linguaMOO. LinguaMOO itself is worth a visit; Jan Rune Holmevik and Cynthia Haynes, who run LinguaMOO, created the web interface we use here at cmcMOO. You might like to have a look at the two other MOOs we as well, Dreistadt for German learners, and Moolin Rouge for French. General MOO resources and links to research papers are available at The Lost Library of MOO.
If you read Norwegian, you can find out a lot more about MOOs and about this and our other projects at lingo.uib's web site.
But if you're here at the Midsummer Night's Dream site in the first place, the best idea is probably to have a look at the Midsummer Night's MOO which is all about Shakespeare's play A Midsummer Night's Dream.