HTML5 & CSS3Tools and Tutorials
Tutorials, tools, and live experimentsOpen Tools

Tutorial Article

HTML <dfn> Tag

The <dfn> tag identifies the defining instance of a term or concept within a document.It is used the first time a term appears, usually alongside its explanation. Browsers may style it in italics by default, but the real purpose is semantic — helping search engines, accessibility tools, and documentation systems understand term definitions. Syntax Attributes [&hellip;]

Nov 21, 2025HTMLHTML TagsTutorials

The <dfn> tag identifies the defining instance of a term or concept within a document.
It is used the first time a term appears, usually alongside its explanation. Browsers may style it in italics by default, but the real purpose is semantic — helping search engines, accessibility tools, and documentation systems understand term definitions.

Syntax

<dfn>term being defined</dfn>

Attributes

AttributeDescriptionValue
NoneThe <dfn> tag has no specific attributes.—

Example

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>DFN Tag Example</title>
</head>
<body>

<p>
    <dfn>HTML</dfn> is a markup language used to structure content on the web.
</p>

</body>
</html>

Output

Browser Output

Use our Tryit Editor to see the output

Browser Support

Chrome
Chrome		Firefox
Firefox		Edge
Edge		Safari
Safari		Opera
Opera		IE
IE9+
✅Yes✅Yes✅Yes✅Yes✅Yes✅Yes

Notes

  • <dfn> marks only the defining occurrence of a term — later references should not use <dfn>.
  • Screen readers may announce it as a “definition”, improving accessibility.
  • Often combined with <abbr> when defining abbreviations.
  • Purely semantic — does not add styling unless styled with CSS.

Conclusion

The <dfn> tag adds meaningful structure by identifying the first definition of a term in your content. It’s simple but valuable for documentation, accessibility, and SEO. Use it whenever you introduce important vocabulary or concepts.