January 2012 - Version 2.2
Read - What's New in Version 2.2

Silverlight is a Rich Internet Application development framework that allows programmers to rapidly create very sophisticated Web applications with a .NET-based development environment. Silverlight, like other Rich Internet Application frameworks, was created to develop advanced applications that are platform/hardware independent; can be distributed and executed over networks (usually through Web browsers); and deliver a sophisticated and seamless desktop-like application experience through a browser without the overhead of a long installation, powerful computing resources, large hard drive, etc.