.CHM File Extension
File TypeCompiled HTML Help File
What is a CHM file?
A CHM file contains help documentation compiled and saved in a compressed HTML format. It may include text, images, and hyperlinks. CHM files are used by Windows programs as an online help solution.
As help documentation has improved and progressed toward website and browser-based formats, the CHM format has largely been retired. Most programs no longer use CHM-based help documentation, and most programs that previously opened CHM files are either unmaintained or no longer open CHM files.
NOTE: CHM files are compressed using the LZX compression format.
How do I open a CHM file?
In Windows, you can open a CHM file by double-clicking it. When you do, the CHM file will appear within Microsoft HTML Help Executable.