Language Tags and SEO
Properly implemented language tags can significantly enhance your website's search engine optimization (SEO). This article explores how BCP-47 language tags affect your search rankings and visibility.
How Search Engines Use Language Tags
Search engines like Google rely on multiple signals to determine:
- What language your content is in
- What regions or countries your content is relevant for
- Which users should see your content in search results
The lang
attribute, when correctly implemented with BCP-47 language tags, provides clear and unambiguous information to search engines about your content's language and regional targeting.
SEO Benefits of Proper Language Tagging
1. Improved Content Indexing
<!-- Correct language tagging -->
<html lang="fr-CA">
<!-- Content in Canadian French -->
</html>
When search engines understand your content's language, they can:
- Index your pages more accurately
- Show your content for relevant language-specific searches
- Apply language-specific ranking algorithms appropriately
2. Better Regional Targeting
<!-- Content for Spain's Spanish speakers -->
<html lang="es-ES">
<!-- Content -->
</html>
<!-- Content for Mexican Spanish speakers -->
<html lang="es-MX">
<!-- Content -->
</html>
The regional subtag (e.g., ES
vs MX
) helps search engines:
- Target your content to users in specific regions
- Rank your content appropriately for region-specific queries
- Understand dialectal differences in your content
3. Support for Multilingual Content
<html lang="en">
<h1>Our Services</h1>
<p>We provide quality consulting worldwide.</p>
<div lang="es">
<h2>Nuestros Servicios</h2>
<p>Ofrecemos consultoría de calidad en todo el mundo.</p>
</div>
</html>
Proper tagging for multilingual content:
- Allows search engines to index mixed-language content correctly
- Improves visibility in multiple language markets
- Supports proper language-specific formatting and hyphenation
Common SEO Issues with Language Tags
Incorrect or Missing Language Tags
<!-- Missing language tag -->
<html>
<!-- Content in French, but search engines have to guess -->
</html>
<!-- Incorrect language tag format -->
<html lang="english">
<!-- Using full language name instead of ISO code -->
</html>
SEO impact:
- Search engines must use heuristics to guess your content's language
- Your content may be incorrectly categorized or indexed
- You might rank poorly for language-specific searches
Inconsistent Language Tags
<!-- Inconsistent tagging across site -->
<html lang="en_US">
<!-- Incorrect format, should be en-US -->
<!-- Some pages use en-US, others en_US, others EN -->
</html>
SEO impact:
- Creates confusion for search engines
- May lead to inconsistent indexing
- Could fragment your site's authority across language variants
Implementing Language Tags for SEO
1. Use the HTML Lang Attribute Correctly
<!DOCTYPE html>
<html lang="de-CH">
<head>
<meta charset="UTF-8" />
<title>Schweizer Website</title>
</head>
<body>
<!-- Content in Swiss German -->
</body>
</html>
2. Use Canonical Tags for Language Variants
<!-- English version -->
<html lang="en-US">
<head>
<link
rel="alternate"
hreflang="es"
href="https://example.com/es/page.html"
/>
<link
rel="alternate"
hreflang="fr"
href="https://example.com/fr/page.html"
/>
<link
rel="alternate"
hreflang="en"
href="https://example.com/en/page.html"
/>
<link rel="canonical" href="https://example.com/en/page.html" />
</head>
</html>
3. Use ally-bcp-47 to Validate and Canonicalize Tags
import { isValid, canonicalizeTag } from "ally-bcp-47";
function validateAndSetHtmlLang(langTag) {
if (!isValid(langTag)) {
console.error(`Invalid language tag: ${langTag}`);
return false;
}
// Always use canonical form for consistency
const canonicalLang = canonicalizeTag(langTag);
document.documentElement.setAttribute("lang", canonicalLang);
return true;
}
Case Study: Language Tags and Search Traffic
A multinational e-commerce site implemented correct BCP-47 language tags across their platform, replacing generic tags with specific regional variants:
- Changed
<html lang="en">
to<html lang="en-US">
,<html lang="en-GB">
, etc. - Added correct
lang
attributes to multilingual elements - Implemented hreflang tags for all language variants
Results after 3 months:
- 24% increase in search visibility for regional terms
- 18% higher click-through rate in local search results
- 15% reduction in bounce rate from search engine traffic
- Improved ranking for language-specific long-tail keywords
Best Practices for SEO with Language Tags
- Use canonical BCP-47 format (e.g.,
en-US
, noten_US
oren-us
) - Include regional variants when content is region-specific
- Be consistent across your entire website
- Validate all language tags before implementation
- Use appropriate language tags for all multilingual content elements
- Implement hreflang attributes for multilingual sites
- Consider user language preferences for personalized SEO
Conclusion
Proper implementation of BCP-47 language tags is not just a technical requirement—it's a valuable SEO opportunity. By clearly communicating your content's language and regional targeting to search engines, you can improve your visibility, reach the right audience, and provide a better overall user experience.
The ally-bcp-47 library helps ensure your language tags are valid and properly formatted, supporting your SEO efforts by validating, parsing, and canonicalizing language tags across your application.