There is only one file type that uses the .NITF extension:
National Imagery Transmission Format File
Imaging data format used by the U.S. government and military for transmitting documents; may contain a combination of text, graphics, and metadata in a single file; also supports multiple layers; often used for satellite and aerial photos.
The NITF format is often used along with the NATO Secondary Imagery Format (NSIF) for storing and transmitting government data.
Updated: March 6, 2011