The Flexible Image Transport System-FITS-has been in use in the astronomica
l community for over two decades. A newly updated version of the standard h
as recently been approved by the International Astronomical Union FITS Work
ing Group. This new version of the standard appears here in its entirety. A
s a preface we briefly describe the process by which the standard evolves a
nd revisions are approved, and note two minor changes to NOST 100-2.0 which
were adopted by the IAU FWG.