The standard data format used in astronomy
Stands for 'Flexible Image Transport System'
Endorsed by NASA and the International Astronomical Union
Much more than just another image format (such as JPEG or GIF)
Used for the transport, analysis, and archival storage of scientific data sets
Multi-dimensional arrays: 1D spectra, 2D images, 3D+ data cubes
Tables containing rows and columns of information
Header keywords provide descriptive information about the data
See also the descriptions on the Wikipedia and Library of Congress Web sites.