In the modern websites, rich internet applications are being extensively used. As a result, research and development work is going on in the field of Web/Internet applications resulting newer and more advanced technologies. Microsoft Silverlight is one of them.

Basically Microsoft Silverlight is an application framework, developed by Microsoft for creating and running RIA or Rich Internet Application which has features like Adobe Flash. RIA generally does not mean a web site with lots of graphics or colour, but a website with lots and lots of functionalities, which are not normally present in those standard websites. As a definition of RIA we can say that RIAs is an internet application which runs in a browser but is as interactive as a desktop application, with much functionality. Microsoft Silverlight has some excellent features which make it a very good application programming interface for creating such applications.

As Microsoft Silverlight applications run in browser, they must be able to run such programs. To be able to run Microsoft Silverlight application program, these browsers must have a plug-in which provides runtime environment for running them. Many modern web browsers like Internet Explorer, Google chrome, Safari, Mozilla Firefox and Opera has this plug in inbuilt.

The facilities and the features offered by Microsoft Silverlight are:

• Microsoft Silverlight provides a graphics system which is very similar to Windows Presentation Foundation or in short—WPF.
• It incorporates multiple features like- multimedia, animation, graphics and interactivity into a single runtime environment. All these features creates awesome user interface by using XAML or Extensible Application Mark-up Language and is programmed by the use of a subset of .NET framework.
• Silverlight can also be used for marking up vector images.
• Besides, Silverlight can support H.264 video, Windows Media Video, MPEG Layer III audio ( MP3 ), Windows Media Audio, VC-1 video and provides an advanced audio coding system.
• Silverlight can also support playback of H.264 dynamically in a web page. (But according to end users license agreement, the H.264 and VC-1 video can only be used for non-commercial use.) Silverlight also supports 3D animations. But the amazing thing about Silverlight is that all these features are available without requiring Windows Media Player ActiveX, Windows Media Player or Windows Media plug-in.
• Silverlight has another great functionality such as, it can dynamically load an Extensible Mark-up Language and manipulate it with the help of DOM or Document Object Modelling technology. This particular feature has provided web developer to use Silverlight as a development tool.

Unlike other Microsoft technology, Silverlight has a free license. It can be used in any platform, browser or any device. The supported platforms are Microsoft Windows 7, Vista, Microsoft Server 2008 R2, Windows server 2008, Windows XP, and Mac OS X. Also, platforms like windows phone and Symbian mobiles can also run Microsoft Silverlight. Although this technology is not used in Linux, open source software Moonlight, developed by the joint venture of Novell and Microsoft, is used to bring Silverlight version 1 and 2 to incorporate with some platforms of Linux, FreeBSD and some other open source platforms.

Many websites uses Microsoft Silverlight for streaming media and animations. Others uses of this technology includes creating awesome UI for websites. The desktop gadget of Windows Vista of Windows 7 uses Microsoft Silverlight.