Using the correct DOCTYPE by Gary Jones

XHTML Doctypes

XHTML 1.1

Files with this doctype SHOULD be served with the application/xhtml+xml mime type.

&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"&gt;

XHTML 1.0 Strict

This is best served as the default text/html so the XML statement is not needed.

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"&gt;

XHTML 1.0 Transitional

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"&gt;

XHTML 1.0 Frameset

Frames are considered to be “not best practice” and so should be avoided. This doctype should only be used on the frameset page.

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"&gt;
&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"&gt;

HTML Doctypes

HTML 4.01 Strict

&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd"&gt;

HTML 4.01 Transitional

&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd"&gt;

HTML 4.01 Frameset

Frames are considered to be “not best practice” and so should be avoided. This doctype should only be used on the frameset page.

&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN"
"http://www.w3.org/TR/html4/frameset.dtd"&gt;

Character set meta tag

This is included for completeness. Stick it the head element so the validators don’t complain.

&lt;meta http-equiv="content-type" content="text/html; charset=utf-8" /&gt;

Gary Jones