Yes it is, but the spec covers only a subset of what people are referring to when they say "HTML5." The official spec [1] outlines what is actually part of HTML

Yes it is, but the spec covers only a subset of what people are referring to when they say "HTML5." The official spec [1] outlines what is actually part of HTML5. This includes a bunch of stuff, like <video>, <audio> and <canvas>, but not the new javascript apis like local storage, drag and drop, web workers and web sockets, nor CSS3, nor SVG, etc. AJAX originally meant (as its name implies) the use of XMLHttpRequest to asynchronously load xml data from a server. However, it quickly became a buzz word that meant increased interactively on a web page outside of the page reload. HTML5 has similarly evolved from describing a limited set of new standards to describe a new way of building highly interactive, desktop-like web applications and encompasses a whole host of W3C standards, recommendations and working drafts. For some evidence that this expanded definition has become the norm, take a look at the HTML5 Test [2], which has been linked here several times. While not anything official, only a handful of the features tested are actually part of the HTML 5 spec. [1] http://www.w3.org/TR/2010/WD-html5-20100624/ http://www.w3.org/TR/2010/WD-html5-20100624/ [2] http://html5test.com/ http://html5test.com/