I wish to a rich user interface for my website. Well, HTML 5 is the best choice. But HTML 5 is still not easy to do some tasks, such as animations and charting. Then, Flash is the second best choice. A lot of platforms support this. But I need to learn it from scratch. In this case, Silverlight is a much better option. It is similar with WPF which I have learnt before.Moreover, the Silverlight is a component-based components. I can use some third-party controls to build the interface. Those third-party controls can be download from internet freely or just needs to pay a small amount of money. This can reduce the amount of coding. So, I choose to learn Silverlight