Silverlight is a development platform for creating engaging web and mobile applications using .NET. It allows visually rich experiences through technologies like HD video, 3D graphics, and animation. Silverlight supports a wide range of platforms and browsers and provides tools for building business and consumer applications. Some key capabilities include media playback, rich graphics, data binding, and cross-platform deployment. Major companies like Netflix, the NFL, and NBC have used Silverlight to deliver interactive video experiences with features like HD streaming, DVR controls, and multiple simultaneous camera views.