HTML lang attribute is set

Screen readers depend on the lang attribute to select the correct language engine for text-to-speech pronunciation. Without it, a screen reader may attempt to pronounce English content using French or Japanese pronunciation rules — producing incomprehensible audio for users who are blind or have low vision. WCAG 2.2 SC 3.1.1 (Language of Page) is a Level A requirement: the lowest, most foundational conformance level. Section 508 (2018 refresh) 504.2 also mandates language identification. A missing lang attribute is an automatic WCAG failure that makes the page non-compliant with accessibility law in the US, EU, and most jurisdictions.

Set the lang attribute on the root <html> element with a valid BCP 47 language code:

<html lang="en">

In Next.js App Router, set it in app/layout.tsx:

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>{children}</body>
    </html>
  );
}

For multi-language sites, set lang dynamically based on the current locale: lang={params.locale}. Common codes: en (English), es (Spanish), fr (French), de (German), pt (Portuguese), ja (Japanese), zh (Chinese).