Microsoft has recently released Silverlight version 2. It is a rich Internet application (RIA) platform. This platform is a subset of the .NET framework. It has the goals of being able to enable media and RIAs. The stated benefit is the ability to leverage existing .NET skills that developers have.
The Visual Web Developer Express IDE is currently a free offering from Microsoft. It supports Silverlight development. Developers are free to use any programming language with Silverlight.
Currently the supported browsers are Internet Explorer, FireFox on the PC and Macintosh, and Apple Safari. Linux browsers are suspiciously absent from the list. There is hope for the Linux community however. The Moonlight project is Silverlight version 1 running on Linux.
The majority of developers use AJAX for RIA purposes now. However that is a primitive option. It also forces you to write complex code which must run on the server for the design to work. Besides, Silverlight has a cooler name than AJAX.
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