I just tried this site
http://validator.w3.org/ Markup Validation Service to see where my new site falls. I had one or two errors it complained about. So I fixed them and all is well.
However for DOCTYPE it reports:
No DOCTYPE Declaration Found!
A DOCTYPE Declaration is mandatory for most current markup languages and without one it is impossible to reliably validate a document.
One should place a DOCTYPE declaration as the very first thing in an HTML document. For example, for a typical XHTML 1.0 document:
<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
How can you tell what kind of DOCTYPE you have?