Silverlight is a browser plugin that allows developers to create rich multimedia web content within a managed .NET environment. It has gone through several versions with new features added at each stage. Silverlight 1.0 provided basic UI controls, media playback, and graphics but lacked managed code support. Silverlight 2.0 added a rich class library compatible with .NET, powerful built-in controls, and extensibility. Silverlight 3 improved graphics capabilities with 3D support, pixel shaders, and tighter integration with Expression Blend tools.