Microsoft Silverlight was released in 2007 as a competitor to Adobe's Flash. A couple years ago Microsoft announced Silverlight is deprecated and announced their transition to HTML5. Companies relying on Silverlight, such as Netflix in 2013, also announced their transition to HTML5.
In May 2015, few users will need Silverlight. Running applications when better alternatives exist can unnecessarily exposes users to security concerns. Microsoft has released KB3056819 to patch Silverlight security vulnerabilities. Anyone who still has Silverlight installed should take this opportunity to uninstall Silverlight.
Click here to have Microsoft your Silverlight installation. Then uninstall Silverlight and hide the Silverlight update: