Windows USER - Implementation

Implementation

In 16-bit versions of Windows, Windows USER was implemented as a file called user.exe. The file extension here was a misnomer, as Windows USER was in fact always a dynamic link library.

In 32-bit versions of Windows, the 32-bit version of Windows USER is called user32.dll, while compatibility with 16-bit applications is provided by having a modified version of user.exe also present.

In 64-bit versions of Windows, the 64-bit implementation of Windows USER is called user32.dll, while a modified 32-bit version (also called user32.dll) is present in the SysWOW64 directory.