EXE
EXE is the common filename extension denoting an executable file (a program) in the DOS, OpenVMS, Microsoft Windows, Symbian, and OS/2 operating systems. Besides the executable program, many EXE files contain other components called resources, such as bitmaps and icons which the executable program may use for its graphical user interface.
EXE file formats
There are several main executable file formats:
DOS
16-bit DOS MZ executable: The original DOS executable file format, these can be identified by the letters "MZ" at the beginning of the file in ASCII.
16-bit New Executable: Introduced with Multitasking MS-DOS 4.0, these can be identified by the "NE" in ASCII. These never became popular or useful for DOS and cannot be run by any other version of DOS, but can usually be run by 16/32-bit Windows and OS/2 versions.
OS/2
32-bit Linear Executable: Introduced with OS/2 2.0, these can be identified by the "LX" in ASCII. These can only be run by OS/2 2.0 and higher. They are also used by some DOS extenders.
Mixed 16/32-bit Linear Executable: Introduced with OS/2 2.0, these can be identified by the "LE" in ASCII. This format is not used for OS/2 applications anymore, but instead for VxD drivers under Windows 3.x and Windows 9x, and by some DOS extenders.
Windows
32-bit Portable Executable: Introduced with Windows NT, these are the most complex and can be identified by the "PE" in ASCII (although not at the beginning; these files also begin with "MZ"). These can be run by all versions of Windows NT, and also Windows 95 and higher, partially also in DOS using HX DOS Extender. They are also used in BeOS R3, although the format used by BeOS somewhat violates the PE specification as it doesn't specify a correct subsystem.
64-bit Portable Executable: Introduced by 64-bit versions of Windows, these are PE files with a CPU type corresponding to a 64-bit instruction set such as x86-64 or IA-64. These can only be run by 64-bit editions of Microsoft Windows running on machines with the CPU type specified in the file.
