Difference Wiki

HTM vs. HTML: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on February 15, 2024
HTM and HTML are file extensions for HTML documents; HTM is used in environments limiting three-letter extensions, while HTML is standard.

Key Differences

HTM and HTML are both file extensions for HTML (HyperText Markup Language) documents. HTM is often used in operating systems and environments where only three-letter file extensions are supported, like earlier versions of Windows. HTML, on the other hand, is the standard extension for these documents on most modern systems, reflecting the full acronym of the language.
When it comes to web development, HTM and HTML files are treated identically. Both contain HTML code, the standard language for creating and designing web pages. The difference in extensions (HTM vs. HTML) does not affect how web browsers interpret or display the content of the files.
Historically, the use of HTM over HTML was primarily a compatibility issue. Older operating systems, specifically DOS-based systems, required three-letter file extensions, hence the creation of .htm as an alternative to .html. Modern systems, however, comfortably recognize and use the .html extension.
In practical use, there is no difference in functionality between HTM and HTML files. Both serve the same purpose: they are text files containing HTML code used to structure content on the web. The choice of extension typically depends on the user's or the system's preference or compatibility requirements.
Despite the historical reasons for the existence of two extensions, HTM is less commonly used today. HTML is widely accepted as the standard extension for HTML files, aligning with the full name of the language. However, HTM still remains in use, particularly in legacy systems or specific software environments.

Comparison Chart

Extension Length

Three-letter extension: .htm
Four-letter extension: .html

System Compatibility

Used primarily in older, DOS-based systems
Standard in modern operating systems

Usage Frequency

Less common, often in legacy systems
More common, universally accepted


Identical to HTML in function
Standard extension for HTML documents

Historical Relevance

Emerged due to three-letter limit
Reflects the full acronym of the language

HTM and HTML Definitions


HTM serves as a compatible option for HTML coding.
Convert the file to .htm for the legacy system.


HTML is the standard language for creating web pages.
Learn HTML to build your own website.


HTM represents older web document formats.
We found several .htm files in the archived website.


HTML is a markup language for structuring web content.
Use HTML tags to format the text.


HTM is used in web development for HTML coding.
Edit the .htm file to update the web page.


HTML is also a four-letter file extension for HTML documents.
Save the document with a .html extension.


HTM is a three-letter extension for markup language files.
The software only recognizes .htm file formats.


HTML forms the building blocks of all web pages.
The website's structure is defined in HTML.


HTM is an alternate file extension for HTML documents.
Save the web page as .htm for compatibility with the old server.


HTML stands for HyperText Markup Language.
HTML is essential for web design and development.


A markup language used to structure text and multimedia documents and to set up hypertext links between documents, used extensively on the World Wide Web.


A set of tags and rules (conforming to SGML) for using them in developing hypertext documents


Are HTM and HTML files different?

No, they function identically; the difference is only in the file extension length.

Is HTML widely used today?

Yes, HTML is the standard language for creating web pages.

Can I convert HTM to HTML?

Yes, you can simply rename the file extension from .htm to .html.

Are HTM files outdated?

While less common, HTM is still used, especially in older or specific systems.

Is HTML used for mobile apps?

HTML is used in web-based mobile applications, often in conjunction with other technologies.

Does HTM support multimedia?

Yes, HTM, like HTML, supports multimedia elements like images and videos.

Is HTML compatible with all operating systems?

HTML is universally compatible with web browsers across all operating systems.

What does HTML stand for?

HTML stands for HyperText Markup Language.

What is HTM?

HTM is an alternate three-letter file extension for HTML documents.

Why does HTM exist?

HTM was created for systems that only supported three-letter file extensions.

Is HTML easy to learn?

HTML is considered a fundamental and relatively easy language for web development.

Can HTM be edited with standard text editors?

Yes, HTM files can be edited with any text editor.

Can HTM and HTML coexist in a project?

Yes, a project can contain both HTM and HTML files without issues.

Does HTM require specific software to open?

No, HTM files can be opened with any web browser.

Can all browsers open HTM files?

Yes, browsers treat HTM files the same as HTML files.

Is HTM still relevant in modern web development?

While HTML is more common, HTM is still relevant in certain contexts.

Can HTML integrate with other programming languages?

Yes, HTML often works with languages like CSS and JavaScript.

What is the main use of HTML?

HTML is primarily used for structuring and presenting content on the web.

Are HTML files text-based?

Yes, HTML files are plain text files containing markup code.

Are HTML and HTM case-sensitive?

The HTML language is not case-sensitive, but file naming could be, depending on the operating system.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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