Microsoft Silverlight is an application framework for writing and running rich internet applications that was designed to be an alternative to Adobe Flash.
Silverlight is supported via plugin for various browsers such as Mozilla Firefox.
The application framework was initially designed to support streaming media, this has now evolved into also support multimedia, graphics, and animation in order to give developers support for common language infrastructure languages and development tools.
Although use of Silverlight it quite well spread, it is one of the application development platforms for Windows Phone, the company announced end of life for Silverlight 5 in 2012.