From HTML WG Wiki
The tagname Element
(This section should contain a short summary of the element, with more specific details provided in the sections that follow.) The tagname element represents...
Explain any best practices here. Use examples to illustrate where appropriate.
Describe any techniques authors should use to help with internationalisation.
Describe any special techniques that authors should use to ensure accessibility.
Include some examples and explanations here. Consider including practical examples that authors would be able to use directly in their own pages. Try to address real use cases where possible.
<html lang="en"> </html>
Link to any other relevant articles, guidelines (e.g. WCAG techniques), tutorials, etc. The quality of these references should be very good and not teach any bad practices.