Microsoft Silverlight is windows counterpart of Adobe Flash Player the dominant standard for multimedia Web applications. It is not used very often on the web as Flash is the standard. Only a very few websites use Silverlight, with the most popular being Netflix. Most people install it as Microsoft keeps pushing it to you with new updates and other sources.
Silverlight is probably unnecessary for you if you don’t use websites which use it. It takes up a lot of space on your hard drive. IT is suggested to avoid installing it and wait until you need it. Microsoft mainly created it to rival with Adobe’s Flash, however it never got as popular. If you already have it install and want uninstall it just Go to Control Panel, select Add or Remove Programs, and Click uninstall with the program selected.
If you get annoyed with Silverlight being preached with every windows update, it is recommended to tick the ‘do not show this again’ box or turn off windows updates at all is even more recommended to avoid annoying features which cause problems and slow down your pc. Even though Microsoft said it is critical to update, nothing will happen if you will not. If you already have it install and want uninstall it just go to Go to Control Panel, select Add or Remove Programs, and follow the prompts.