Definition Filename Extension
Explanation: Filename extension is a portion of a filename, following the point after the individual file name. Filename extenson indicates the type of data stored in the file. Many operating systems use filename extensions, e.g. Unix,MS-DOS. Examples include "c" for C source code, "doc" for Miscrosft word, "ps" for PostScript, "txt" for text fle, etc.
Other definitions in programming such as Filename Extension in Dictionary F.