HTML check: This document appears to be written in English but the “html” start tag has an empty “lang” attribute. Consider using “lang="en"” (or variant) instead.

About This HTML Issue

The lang attribute on the <html> element declares the primary language of the document’s content. When this attribute is left empty (lang=""), it effectively tells browsers and assistive technologies that the language is unknown or intentionally unspecified — which is almost never what you want.

This matters for several important reasons:

Accessibility: Screen readers rely on the lang attribute to select the correct pronunciation engine. An empty value can cause a screen reader to fall back to a default language, potentially reading English text with incorrect pronunciation rules.
Search engines: Search engines use the lang attribute to understand what language your content is in, which helps serve your pages to the right audience.
Browser features: Browsers use the language declaration for hyphenation, spell-checking, font selection, and other language-sensitive rendering decisions.
Standards compliance: The WHATWG HTML living standard specifies that if the lang attribute is present, its value must be a valid BCP 47 language tag. An empty string is not a valid language tag.

The fix is straightforward: set the lang attribute to a valid BCP 47 language tag that matches your content. For English, common values include en (general English), en-US (American English), or en-GB (British English). If your content is in another language, use the appropriate tag (e.g., fr for French, de for German, ja for Japanese).

Examples

❌ Empty `lang` attribute (triggers the warning)

<!DOCTYPE html>
<html lang="">
  <head>
    <title>My Page</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
  </body>
</html>

❌ Missing `lang` attribute entirely

While a missing lang attribute triggers a different warning, it causes the same underlying problem — no language is declared:

<!DOCTYPE html>
<html>
  <head>
    <title>My Page</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
  </body>
</html>

✅ Correct: specifying the language

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>My Page</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
  </body>
</html>

✅ Correct: using a regional variant

<!DOCTYPE html>
<html lang="en-US">
  <head>
    <title>My Page</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
  </body>
</html>

Using `lang` for mixed-language content

If your document is primarily in English but contains sections in other languages, set lang="en" on the <html> element and override it on specific elements:

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Multilingual Page</title>
  </head>
  <body>
    <h1>Welcome</h1>
    <p>This page contains a quote in French:</p>
    <blockquote lang="fr">
      <p>La vie est belle.</p>
    </blockquote>
  </body>
</html>

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Learn more:

W3C Reference

W3C: Declaring language in HTML

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