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HTML Validation

The “icon” element is a completely-unknown element that is not allowed anywhere in any HTML content.

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About This HTML Issue

The <icon> element does not exist in HTML. No version of the HTML specification defines it, and browsers do not recognize it.

This error appears when markup includes <icon> as if it were a standard HTML element. It is not. Browsers will treat it as an unknown inline element with no default behavior or semantics. To display icons, use an <img> element, an <svg> element, or a <span> with CSS-applied background images or icon fonts.

If the intent is to define a favicon (the small icon shown in browser tabs), the correct approach is a <link> element inside <head> with rel="icon".

HTML examples

Invalid: using the <icon> element

<head>

  <title>My page</title>

  <icon src="favicon.png"></icon>

</head>

Valid: using a <link> element for a favicon

<head>

  <title>My page</title>

  <link rel="icon" href="favicon.png" type="image/png">

</head>

Valid: displaying an icon inline with <img>

<p>

  <img src="star.svg" alt="Star" width="16" height="16"> Favorite

</p>

Valid: displaying an icon inline with <span> and CSS

<p>

  <span class="icon icon-star" aria-hidden="true"></span> Favorite

</p>

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Learn more:

MDN Reference
HTML elements reference - MDN
→
WHATWG Spec
HTML Standard - Semantics
→

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