LambdaMOO is a network-accessible, multi-user, programmable, interactive system well-suited to the construction of text-based adventure games, conferencing systems, and other collaborative software. Its most common use, however, is as a multi-participant, low-bandwidth virtual reality, and it is with this focus in mind that I describe it here. See also /usr/local/share/doc/LambdaMOO. WWW: http://www.moo.mud.org/