file format A format for encoding information in a
file. Each different type of file has a different file format. The file format
specifies first whether the file is a binary or ASCII file, and second, how the
information is organized.
file extension One or several
letters at the end of a filename. Filename extensions usually follow a period
(dot) and indicate the type of information stored in the file. For example, in
the filename EDIT.COM, the extension is COM, which indicates that the file is a
command file. Depending on the operating system, the punctuation separating the
extension from the rest of the filename may or may not be considered part of the
extension itself.