Which Help should I choose?
Normally we use HTML HELP (.chm) unless integrating into VS help or Windows help.
- WinHelp (.hlp)
Deprecated. No longer ships with Windows OS (Vista and above). Move your authoring to HTML Help. A crippled WinHelp32.exe is still available for download. WinHelp is also the help system used for older versions of MSDN and VS,
- HTML Help (.chm)
Use for all general application help. Also the help system used for older versions of MSDN and VS,
- MS Help 2 (.HxS)
Use for Visual Studio 2002/2003/2005/2008 help integration.
- AP Help (.H1S)
Use for Windows Vista OS/OEM system help.
- Help Viewer (.mshc)
Use for Visual Studio 2010/2012/+ help integration. Also ships with Windows 8 OS (for Windows and OEM help).