What the heck is HTML 5?

The document discusses the evolution of HTML over time. It notes that XHTML proposals broke backwards compatibility and saw slow adoption. Meanwhile, browsers and technologies like Ajax advanced independently of standards bodies. This led to the formation of the WHATWG to further develop HTML. HTML 5 is described as just a nickname for ongoing incremental HTML revisions, combining the work of the WHATWG and W3C, allowing both XML and classic HTML syntaxes.