HTML5, XHTML2, and the Future of the Web: “HTML 4.01 was made a recommendation in 1999, XHTML 1.0—a formulation of HTML 4.01 in XML—became a recommendation in 2000, and was revised in 2002. In other words, at the base of all modern web development is an eight-year-old technology.”

Link:
http://…/html5_xhtml2_and_the_future_of_the_web/