What is a .CHM File Extension?
Files that have .chm file extensions are generally a set of Hyper-Text Markup Language (HTML) kind of web pages that have hyperlinked contents. These files are mostly used in HTML help files that come in every software packages given that users who acquire these software programs will be provided with more information regarding the purchased software. These HTML Help files contain hyperlinks that connect them to the software developer’s website or some other necessary sites.

The purpose of these .chm Help files is to allow the user’s computer to navigate necessary files of documents when the user accessed the help section of the application.  Additionally, these files with .chm file extensions are used in e-books. They are used for displaying web contents.

What do files with .chm file extensions look like?
Files with .chm file extensions are designed for reading purposes only. These files are indexed heavily. Files with .chm file extensions contain:

1. Text
2. Images
3. Hyperlinks

In addition, this file extension was created by Microsoft. Therefore, it will run mostly on Microsoft supported programs and applications. These programs are as follows:

• Help Explorer View
• xCHM
• GridinSoft CHM Editor/CHM Decoder
• Help Software CHM
• DawningSoft PowerCHM
• CHM Decompiler
• Web browsers

-Mozilla Firefox

-Internet Explorer

These files may also run into different operating systems such as Mac and Linux
Mac programs that support files with .chm file extensions are:

• CHMox
• CHM Viewer
• xCHM
• Web Browsers

-Safari

-Mozilla Firefox

Linux Programs that support files with .chm file extensions are:

• Help Explorer Viewer
• xCHM

Unless the user has programs that allows them to view or open these .chm files, trying to open it will only display an error message. The format of these .chm files may contain a threat, particularly in security purposes. These .chm files’ capabilities allow them to hold and perform arbitrary coding which makes them a threat to security. These are some disadvantages of files with .chm file extensions:

1. A security risk
2. Some network security protocols do not allow some files with .chm file extensions to be viewed.
3. Files with .chm file extensions are affected every time Windows operating systems patches.
4. UNICODE is not supported by these HTML Help Files.

Although the use of .chm file extensions may have some disadvantages, it also yields greater benefits such as:

1. Files with .chm file extensions have smaller file size rather than just plain HMTL
2. This allows HTML to have a wide range of options particularly in text managements.
3. This allows users to easily track and search for full sentences or texts.
4. It is easier to arrange and organize files with .chm files extensions in one particular TOC, search and index.
5. Allows users to produce TOC also Subject Folder that holds international letters and characters. These productions does not generated correctly by Basic HTML

The file begins in a standard format with bytes Info-tech Storage Format (ITSF) and is being compiled through hhc.exe (Windows Operating Systems)

If the files with .chm file extensions cannot be opened and it displays an error, this error might be cause by:

1. An unidentified program that is not suitable to open the file with the .chm file extension.
2. The registry might be damaged and it can no longer support the program that reads the file.