32-bit Help files have been around for a long, long while. Based on Rich Text Format, these files are a proprietary format for Windows computers. Windows XP was the last operating system version to include WinHelp viewer, yet the popular file format has continued to be used. WinHelp originally shipped with Windows 3.0 in 1990 and due to many vendors still utilizing these types of files and because a multitude of older applications are still in use, Microsoft has had to update the viewer application with each operating system after Windows XP. In 2006, Microsoft announced intentions to phase out support for the help file platform stating that it simply no longer met the standards set forth as they planned the development and release of Windows Vista.
The latest update has released to bring support for viewing .hlp files for Windows 8.1, and you can find it here: Windows Help program (WinHlp32.exe) for Windows 8.1
Note that this is for Windows 8.1 ONLY.
If you've not upgraded from Windows 8 to Windows 8.1 yet, there's also one available for Windows 8 that was released in October 2012: Windows Help program (WinHlp32.exe) for Windows 8
And, if you're just now somehow figuring out that you need to read .hlp files in Windows 7 and Windows Vista, the downloads for those operating systems are here: