EXE is the common filename extension for denoting an executable file (a program) in the MS-DOS and Microsoft Windows operating systems. Generally, "exe" may be used as a noun to refer to such a file.

There are three main EXE file formats.

• DOS executable: These can only be identified by the ASCII MZ or the hexadecimal 4D 5A at the beginning of the file. These executables are the least complex in DOS/Windows and can be run from both.
• 16-bit executable: These can be identified by the NE in ASCII. These cannot be run by DOS but can be run by all Windows operating systems.
• 32-bit Portable Executable: These are the most complex and can be identified by the PE in ASCII. These can only be run by Windows 95 and higher.

When a 16-bit or 32-bit executable is run by Windows, execution starts at either the NE or the PE. On the other hand, DOS cannot execute these files. To prevent DOS from crashing, all Windows executable files must start with a working DOS program. Normally this program simply displays a message that it cannot run in DOS mode, but some Windows programs (such as regedit) have a usable DOS section.

External links

• EXE header format
• Dependency Walker