Content optimisation
Language attribute
html element declares a valid lang attribute
What we check
html element declares a valid lang attribute
Why it matters
The lang attribute tells browsers and screen readers which language to use.
How to fix it
Add lang to the html element, for example <html lang="en">.
How it affects your score
This check sits in Content optimisation, which is worth 30% of the overall score. A critical result costs the full weight of the check; a warning costs half. If we can't measure it on your page, we leave it out of the score entirely.