WinHelp is the traditional standard help system for the Windows platform. WinHelp content is typically delivered as files with a .hlp extension.
The WinHelp system features graphical hypertext rendering, table of contents, index lookup, full-text keyword search. Originally designed to be a consistent delivery mechanism for software application user help content. It has later been used to deliver training guides, interactive books, newsletters, references.
Microsoft has developed another help system called HTMLHelp. Although the WinHelp format will still be supported on the Windows platform, it is expected that most newly developed help content will be delivered using the newer HTMLHelp system and the WinHelp format will be gradually phased out.