Use valid language codes in the lang attribute
Accessibility isn’t only about avoiding violations — it’s about ensuring your product can be used confidently by everyone. This guide explains the principle of this rule, shows what goes wrong in real-world code, and provides a verified fix that meets WCAG and the European Accessibility Act (EAA).
Why this matters and how to fix it
Why this matters
Invalid language codes prevent assistive technologies from determining pronunciation rules. For example, `lang='english'` is invalid — it must be `lang='en'`.
How to fix this issue
Use only ISO language codes as defined by BCP 47 (e.g., 'en', 'sv-SE', 'de', 'fr-CA').
Developer guidance
Check your code with validators or use automated linting tools to enforce valid language tags.
Code examples
Incorrect Implementation
<html lang='english'></html>Correct Implementation
<html lang='en'></html>
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