See also: Polish translation of this page as of June 2007
The WHATWG works on a number of technologies that widely get referred to by the buzzword "HTML5".
These technologies are all published in the HTML standard, parts of which are republished as an edition optimized for Web developers.
The HTML standard is a continuously maintained living specification, with maturity managed at a very granular per-section scale, indicated by markers in the left margin; this is intended to model the way in which specifications are approached in practice by implementors and authors alike.
For more details, please see the relevant FAQ entry.