HITRAN is an acronym for high-resolution transmission molecular absorption database. HITRAN is a compilation of spectroscopic parameters that a variety of computer codes use to predict and simulate the transmission and emission of light in the atmosphere. The database is a long-running project started by the Air Force Cambridge Research Laboratories (AFCRL) in the late 1960's in response to the need for detailed knowledge of the infrared properties of the atmosphere. The current edition of the HITRAN molecular spectroscopic database and associated compilation (v13.0) is available on an ftp site located at the Smithsonian Astrophysical Observatory in Cambridge, USA. Updates and corrections to the compilation will be made available on this web-site under the sub-page HITRAN UPDATES.