Filename extension

filename extension
    n 1: a string of characters beginning with a period and followed
         by one or more letters; the optional second part of a PC
         computer filename; "most applications provide extensions
         for the files they create"; "most BASIC files use the
         filename extension .BAS" [syn: {extension}, {filename
         extension}, {file name extension}]
    

filename extension
file extension

   <filename extension> The portion of a filename, following the
   final point, which indicates the kind of data stored in the
   file.

   Many {operating systems} use filename extensions, e.g. {Unix},
   {VMS}, {MS-DOS}, {Microsoft Windows}.  They are usually from
   one to three letters (some sad old OSes support no more than
   three).  Examples include "c" for {C} {source code}, "ps" for
   {PostScript}, "txt" for arbitrary text.

   {NEXTSTEP} and its descendants also use extensions on
   directories for a similar purpose.

   Apart from informing the user what type of content the file
   holds, filename extensions are typically used to decide which
   program to launch when a file is "run", e.g. by
   double-clicking it in a {GUI} {file browser}.  They are also
   used by {Unix}'s {make} to determine how to build one kind of
   file from another.

   Compare: {MIME type}.

   Tony Warr's comprehensive list
   (http://camalott.com/~rebma/filex.html).

   FAQS.org Graphics formats
   (http://faqs.org/faqs/graphics/fileformats-faq/).

   (2002-04-19)