HTML 5

HTML 5: "HTML from the start never really enforced any strict rules about its markup. As a developer, this was a feature, but it makes the HTML interpreter's task increasingly complicated. Therefore, towards the end of the 90's W3C started working on XHTML, which was a revised form of HTML 4.1 but it, based itself on XML, which was much stricter about the markup. Thereafter, W3C was maintaining and updating two parallel languages, HTML 4.x and XHTML 1.x. XHTML 5 is now being defined alongside HTML 5 in the HTML 5 spec draft."