.HLP -- Proprietary file generated by MS Help Workshop.
Project files: HPJ, CNT, RTF, BMP, SHG -- RTF file based. Multiple topics in one file.
Runtime: Windows 3.0 OS or greater. Discontinued in Windows Vista.
Microsoft's WinHelp (.hlp files) and Help Compiler Workshop (hcw.exe), first popular in early Windows 3.0. WinHelp stopped shipping with Windows Vista. A crippled version of the WinHelp runtime (WinHelp32.exe) can still be downloaded from the MS site.
15-Mar-2006 — MS Announce WinHelp to be Deprecated. During discussions with MVPs, Microsoft Help team announced today that WinHelp would be deprecated (phased out). Ted Dwonkin (MS) told MVPs: WinHelp is architected in such a way that we would have to rewrite it from the ground up to meet the Vista code standards. And that approach doesn't make sense given that we have two other Help systems in Vista.
What does this mean?
See also MVP Dana Worley's comments
The four components of a WinHelp file are the .HPJ file, the .RTF file, the .CNT file, and Microsoft's WinHelp compiler (http://helpmaster.helpmvp.com/hlp-musthave). Regardless of the tool you use, all of them are using these same basic components. The HPJ file is the file that tells the compiler what the help file should look like, the RTFs to use when compiling, and the context IDs for linking the help topics into the application. The CNT file is basically the Table of Contents for the help file. The RTF file is the "guts" of the help file. It contains all the topics that should be included in the HLP.
What's the best help authoring tool to use?
A tool comparison, as well as a list of tool vendors, white papers on helping you choose the right tool, etc.
Win Help tutorials and whitepapers, Win Help programming.