A11ying with Sanna - Web Content Accessibility Guidelines a guide to the accessibility requirements
3 Understandable

3.1.2 Language of Parts

Conformance level: AA
Criterion released in WCAG version: 2.0

Official description of the success criterion

The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text.

What to do?

Identify the language of each passage or phrase.

Why is it important?

Ensures proper pronunciation by screen readers.

Common pitfalls

Adding content to a page in another language without adding the lang attribute for that content.

How to test for it?

Check if there is content in another language on the page. Check those for the correct lang attribute.

Exception: proper names, technical terms, words of indeterminate language and words or phrases that have become part of the vernacular of the immediately surrounded text.

More about this criterion elsewhere