Question: I am having trouble finding a clear answer on this one. I have an ASP.NET 4.0 Silverlight app, but recently a ton of users are complaining about not being able to use the site on mobile devices and Linux distro's. The app is built on MVVM architecture, and thus we are considering changing the UI to alleviate the complaints. We are leaning toward HTML5, but I'm not sure if this is even technically possible with ASP.NET 4.0. I've seen some posts saying that HTML5 only works with javascript code behinds, and that with ASP.NET 4.5 HTML5 support will be added. Am I understanding this correctly? Maybe it would make more sense to just go with an ASPX UI, what are the advantages of HTML5 over .ASPX? Any help is appreciated.

Answer: 
HTML5 is a set of client-side technologies.  

ASP.Net is a server-side technology.  

They have nothing to do with each-other.

However, it will be easier in ASP.Net MVC.
HTML5 works in conjunction with Javascript on the client side. You can still use ASP.NET to process data and deliver content server side. Here are some quick links.

<http://visualstudiomagazine.com/articles/2011/09/01/pfcov_html5.aspx>  

<http://mvchtml5.codeplex.com/> (I know it's mvc, but it might be helpful regardless.)