W3C QA - Recommended list of Doctype declarations you can use in your Web documentWarning The list is informative and does not try to be exhaustive (there are many other proper declarations you could use), but it has most of the declarations commonly used on the Web at the moment. Recommended Doctype Declarations to use in your Web document. When authoring document is HTML or XHTML, it is important to Add a Doctype declaration. This makes sure the document will be parsed the sa
