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- The primary language of the page MUST be identified accurately on the <html> element.
- The primary language of the page MUST be identified with a valid value on the <html> element.
- Inline language changes MUST be identified with a valid lang attribute.
- The language code MUST be valid.
Non-required / best practice
Headings
Required
Headings MUST be accurate and informative.
Non-required / best practice
Text that acts as a heading visually or structurally SHOULD be designated as a true heading in the markup.
Text that does not act as a heading visually or structurally SHOULD NOT be marked as a heading.
Heading text SHOULD be concise and relatively brief.
Headings SHOULD convey a clear and accurate structural outline of the sections of content of a web page.
Headings SHOULD NOT skip hierarchical levels.
The beginning of the main content SHOULD start with <h1>.
Most web pages SHOULD have only one <h1>.