This document discusses extending SharePoint 2010 with HTML 5 features. It provides a brief history of HTML and CSS standards. It then covers leveraging new HTML5 features in SharePoint 2010 like responsive design, adding support for newer browsers like IE9, and providing fallback support for older browsers like IE8 and IE7 through techniques like polyfills and Modernizr. The document demonstrates these concepts through examples and references additional resources for learning HTML5.