The (often large) online reference document for an application. A program's help file will usually be in Windows Help format or HTML format. To display the help file, the user must run software that is not part of the application (such as Windows Help), but usually the operating system makes this transparent to the user. Typically, a user accesses a topic in the help file by clicking the Help button on a window. The user may also navigating the help file by hyperlinks or look up specific topics via search features in the software that displays the help file. A software developer typically creates the help file with a tool such as Doc-To-Help or RoboHelp. See: Popup Help.