As most of you have already heard about HTML5 and CSS3 , which are the next generation web technologies and so most of the web sites are migrating to them.
These are already supported by latest versions of many browsers including mobile browsers.
Beyond Microsoft’s involvement with the W3C and the HTML5 technologies supported in the browser, there’s another dimension to Microsoft’s approach to HTML5 that’s important for developers: its approach to HTML5 tooling. In early 2011, Microsoft updated two of its development tools with service packs: Visual Studio 2010 and Expression Web 4. The service packs for both of these tools provided an HTML5 document type for validation, as well as IntelliSense for new HTML5 tags and attributes
WebMatrix makes it easier for you by providing an HTML5 document by default.
Microsoft further updated its HTML5 support with its release of the Web Standards Update for Microsoft Visual Studio 2010 SP1 in June 2011. This extension, which works with all editions of Visual Studio 2010, adds further HTML5 IntelliSense and validation to Visual Studio, includes JavaScript IntelliSense for new browser capabilities like Geolocation and DOM Storage, and provides comprehensive CSS3 IntelliSense and validation
http://msdn.microsoft.com/en-us/magazine/hh335062.aspx
http://dev.w3.org/html5/spec/Overview.html
