In computer terminology, anything “executable” is able to be run on a computer. Normally, when a user types a filename (as opposed to an internal command built into the command interpreter or shell) as the initial word on the command line, the command processor searches for a file with that name to run. On Windows systems, for example, the extensions .EXE and .COM indicate that it contains a program; .PIF or .LNK indicate that it has information for executing a program; and the extensions .BAT, .BTM, or .CMD indicate that it is a batch file.
Default extensions for executable files differ somewhat, depending on the operating system used and the command interpreter utilized; each operating system has its own rules for executable file extensions. UNIX and Linux systems, for example, do not use extensions to identify executable files; instead, an “executable” flag in the file system is used for this purpose.
JP Software, Inc. Executable Extensions. [Online, December 16, 2003.] JP Software, Inc. Website. http://www.jpsoft.com/help/index.htm?exeext.htm.