What browsers does Silverlight run in and what browsers and versions of browsers does Silverlight not run in? What are the browser formats to be concerned with if you want your web site to be viewed universally? I mean, if you can develop a cool silverlight app, I know that Silverlight does not run on Internet Explorer 64 bit. So I guess I would have to use HTML 5 for that. What about the other browsers and platforms and what would be the replacement technologies?