The Shell Light-Weight API

Some time at least as long ago as mid-1996, Microsoft started gathering a collection of mostly small and mostly self-contained functions for a shell utility library. Many of these functions had previous implementations in the Windows 95 or NT 4.0 versions of either the shell itself (SHELL32.DLL) or the common controls library (COMCTL32.DLL) or both.

The result, named SHLWAPI.DLL, seems to have been released first for Windows 95 OSR2 and Internet Explorer 3.0. It has ever since been a core component of the standard shell in those Windows operating systems that derive from DOS, but did not become a core NT component until Windows 2000.

SHLWAPI has shipped with all subsequent releases of Internet Explorer. Indeed, its functionality seems to have expanded most for releases of Internet Explorer rather than of any operating system. A significant expansion was released in Internet Explorer 4.0 well ahead of Windows 98. Another was released in Internet Explorer 5.0 well ahead of Windows 2000 (and even a little ahead of the relatively minor Windows 98 Second Edition). This fits broadly with other reasons to infer at Microsoft an attitude, sustained over several years, that customers of Microsoft’s operating systems who want to upgrade their operating system might best do so by acquiring Microsoft’s web browser.