What is Silverlight?

Silverlight is a web based technology, launched by Microsoft in April 2007. Silverlight is considered as a competitor to Adobes Flash.
Silverlight is a powerful cross-browser & cross-platform technology for building the next generation web experience & rich internet applications for the web. You can run Silverlight in most of all the popular browsers like Internet Explorer, Firefox, Chrome, Safari etc. Silverlight can run in various devices and operating systems like Windows, Apple Mac OS-X and Windows Phone 7. Using Silverlight you can create rich, visually stunning web applications like flash. Also you can create smooth animations using Storyboards; you can stream media over the net etc.
Silverlight web browser plug-in comes as free to install (approximately 4-5 MB in size). You can download the required plug-in from Microsoft Silverlight Site.
Silverlight applications are delivered to browsers in a text-based markup language called XAML. One important difference between Flash and XAML is, Flash is a compiled application where as XAML is text based. Search engines can analyze and index such content, which is a huge benefit for webmasters.
For regular internet users, Silverlight is a browser plug-in that supports video, audio and animations.
For web developers, Silverlight offers much more. Silverlight supports video and audio files without need of much programming. It allows them to handle events from web pages (like handle start/end of video playing etc)