IAO may mean several things: · The Information Awareness Office, a branch of the U.S. Defense Advanced Research Projects Agency. · The International Astronomy Olympiad, an internationally recongnized annual astronomy competition for high-school students. · The Indian Astronomical Observatory, home of the highest telescope in the world. · The initials of Isis, Apophis and Osiris, used as a magical formula in the Hermetic Order of the Golden Dawn. · The [LINK: Incorporated] Association of Organists, a UK based organisation to which Societies of Organists generally subscribe. It publishes a journal, Organists Review. · Individual Artists of Oklahoma (IAO) is a non-profit arts organization located in Oklahoma City, Oklahoma, USA. IAO