What is Microsoft Silverlight? [duplicate]

It's basically Microsoft's version of flash. It is a web application framework initially made for video streaming, but now has many more features and .NET language support. The majority of videos on Microsoft's website are using it, and other sites are popping up using it as well. If you use MSDN or are interested in any of the programming video tutorials on their site, Silverlight is a must have. More on it here.