Microsoft HTML-Help replaces Winhelp in Windows 98 and Windows 2000. It's based upon HTML: a number of HTML files with some Microsoft-specific (non-official) HTML extensions are the input for the HTML-Help compiler. This compiler creates a binary file with the extension CHM (compiled HTML). Additional functionality to normal HTML files is tree view contents (HHC file) and an index (HHK file).
The project file for executing with the MS HTML-Help compiler has got the extension HHP (HTML Help Project).
Because of the ability of Windows 98 and NT 5.0 to run Windows 3.1 and Windows 95 programs, the Winhelp format will be supported too for a long time.
You can download the MS HTML-Help compiler from the Microsoft Homepage http://www.hypermake.com and then search the expression HTML-HELP.
The HTML-help viewer HH.EXE is not part of Windows 95 and NT 4.0 and will be only
part of Windows 98 and NT 5.0. If you do not write both a Winhelp and
a HTML-Help file for your application (not very difficult when using Hypermake!),
HH.EXE has to be part of your software package.