Here are the doctype declarations for you. Short and sweet HTML Doctypes: HTML 5 Doctype HTML 4.01 Strict Doctype XHTML Doctypes: XHTML 1.1 Doctype XHTML 1.0 Transitional Doctype XHTML 1.0 Strict Doctype Read more here. *Something to note – If you use TinyMCE it tries to produce XHTML compliant code, not HTML.  That being said, I’ve … Continue reading Doctype Reference – HTML and XHTML