CHM is a proprietary format for online help files. They have a set of web pages written in a subset of HTML and a hyperlinked table of contents. CHM format is optimized for reading, as files are heavily indexed. All files are compressed together with LZX compression. Most CHM browsers display a table of contents on the left.
A CHM help file has a ".chm" or ".CHM" extension and is often referred to as a "chum" file. The file starts with bytes "ITSF" (in ASCII), for "Info-Tech Storage Format". The format has been partially reverse engineered and there are container and internal files specifications available.
- file size smaller than plain HTML
- range of formatting options that HTML gives for text presentation
- ability to search the full text
- ability to assemble several CHM files into one file with common TOC, index and search (see MSDN)
WinCHM is a very easy-to-use help authoring tool. Not needing to learn too much, you can be master of creating HTML help(CHM), Web help, PDF and Word documents. Using WinCHM you can not only make help files with nothing, but also convert a set of HTML files into a CHM file.