) is preferred for all HTML documents: <code>&lt;!DOCTYPE html&gt;</code>.</p>

<p>(It’s recommended to use HTML, as <code>text/html</code>. Do not use XHTML. XHTML, as
<a href="https://hixie.ch/advocacy/xhtml"><code>application/xhtml+xml</code></a>, lacks both browser
and infrastructure support and offers less room for optimization than HTML.)</p>

<p>Although fine with HTML, do not close void elements, i.e. write <code>&lt;br&gt;</code>, not <code>&lt;br
/&gt;</code>.</p>

<h4 id="HTML_Validity" class="