What Does Microsoft Silverlight Do?

By G.D. Palmer

Microsoft Silverlight is an application framework similar to Adobe Flash. This framework was designed to help write and run what are called "rich Internet applications," or RIA. RIAs include streaming media, animation, multimedia and other functions that a basic Web browser can't handle. Microsoft Silverlight is a relative newcomer to the field of RIA frameworks, first appearing in 2007.


Silverlight 1, developed as Windows Presentation Foundation/Everywhere, was released in 2007. It included only the core presentation framework and could handle graphics, animation, digital rights management (DRM), media playback and a few other features. Silverlight 2 included Microsoft's .NET Framework, allowing it to execute programs written in .NET languages. Silverlight 3, released in 2009, offered more controls and layout panels as well as support for 3-D transformations of two-dimensional elements. Silverlight 4, released in April 2010, included support for the Google Chrome browser, webcams, microphones and many new controls.

Streaming Video

Microsoft Silverlight supports streaming video via its IIS Smooth Streaming. This feature allows streaming of on-demand and live media using standard HTTP protocol, and scales to work on large-distribution networks. This feature is designed to provide a quality visual experience for viewers, even if they have relatively low-quality connections or older computers.

Deep Zoom

Silverlight's Deep Zoom feature allows users to zoom in on high-resolution pictures with relatively low load times. It optimizes the way the computer stores the images, downloading only the information needed to fill the screen. This reduces the amount of data that needs to be transferred at once, allowing users with low-end computers to zoom in on large pictures without the need to wait.

Media Format Extensibility

Silverlight 4 uses a Raw AV pipeline that allows it to support a wider range of audio and video formats than before. It decodes third-party media formats, and then re-renders them in Silverlight. This extends format support outside Silverlight's native Microsoft-branded formats.


Silverlight offers relatively easy skinning and styling, so designers can customize the look and feel of scroll bars and other controls. The framework's XAML-based templates allow designers to change the look and layout without rewriting its basic code. This allows websites running Silverlight to avoid a pre-packaged look and make the most of the available design options.


Microsoft Silverlight is available on Windows and Macintosh machines, and is compatible with Internet Explorer, Firefox and Chrome on Windows systems. Macintosh users who wish to use Silverlight must run either Firefox 3+ or Safari 3+. Microsoft does not offer Silverlight on Linux-based systems. However, Novell offers a framework called Moonlight to allow Linux users to enjoy Silverlight-based web pages and other media.