What is a CHM?
A CHM help file has a ".chm" extension. It has 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 have the capability to display a table of contents outside of the body text of the help 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.
On Windows computers, this help file can be compiled using hhc.exe. There are some open source tools which can read and explore these files, but they lack various features of the Microsoft Windows tools, most importantly a write support.
Question about CHM : CHM is not opening in my Browser
I have downloaded a CHM file but i can not open it.
It keeps showing a dialog box titiled "Help" with the content as follow."Cannot open the file: ...."
You cannot open HTML Help files from Internet Explorer after you install security update 896358 or Windows Server 2003 Service Pack 1
This is Microsoft Security Issue, read this article: http://support.microsoft.com/?scid=kb%3Ben-us%3B902225
You can get more CHM based Softcopy Ebooks from http://www.pdfchm.com