HTML5 is the next version of Hypertext Markup Language (HTML), under development by the Web Hypertext Application Technology Working Group (WHATWG) in conjunction with the World Wide Web Consortium (W3C). HTML5 sets out to create better interoperability across tools. Much cleanup is being done for the authoring of new content. Markup that is better served by CSS will no longer be available for authoring. Distinction is drawn between what should be supported for authoring content versus what should be supported in tools. Browsers should be backwards compatible, while content should be written to new recommendations. HTML5 will not move from working draft to recommendation status until there have been at least two successful implementations proving that the recommendation is viable.

As the HTML 5 draft evolves, browser developers are working to incorporate new features and specifications. The progress of Internet Explorer, Firefox, Safari, Opera and Chrome are being documented on the Web Hypertext Application Technology Working Group(WHATWG) wiki. You can begin testing features in current releases of most popular browsers.