This document discusses HTML5 features and how they relate to PHP development. It begins by noting that HTML5 moves from documents to applications and from hacks to solutions. It then discusses how technologies like Ajax, Comet, and real-time updates have led to a change where content is less important than context and applications like Facebook and Twitter are really applications, not just pages. The document outlines several new HTML5 features like WebSockets, Web Workers, offline applications, geolocation, drag and drop, and the file API. It argues that more logic will move to the client and browsers with these features. The summary concludes that HTML5 is part of a new application framework and that PHP developers will need to learn JavaScript to