Answer - To run Silverlight applications in a web browser, you need to have the Silverlight runtime installed on the client browser as a plug-in. This is a light-weight version of the .NET runtime. However, to develop a Silverlight application, you need something more. Silverlight SDK: This includes a set of tools required to compile and build Silverlight controls. If you are comfortable writing HTML using Notepad and compiling .NET applications from console tools, then you just need the Silverlight SDK to develop Silverlight applications. However, most people use some kind of IDE to develop applications faster. Microsoft offers two separate tools to develop Silverlight applications: • Microsoft Expression Studio - This tool is meant for web designers to create rich visual elements for Silverlight applications. Expression Studio is recommended for web designers who create rich internet applications with enhanced visual content and graphics. There are several features provided for creating enhanced graphics elements, with lot of options to pick color, font, etc. • Microsoft Visual Studio - This is the integrated development environment from Microsoft to develop .NET applications. Programmers can use Visual Studio to develop Silverlight applications which require programming. Visual Studio allows programmers to develop sophisticated Silverlight applications in any .NET language (like C#, VB.NET etc). Here are some other tools that you can use: • Install Deep Zoom Composer - This tool allows you to prepare your images for use with the Deep Zoom feature in Silverlight 3. • Download Silverlight Toolkit - This toolkit is a Microsoft project containing Silverlight controls, components, and utilities that can be downloaded and used in your Silverlight applications. It includes full source code, samples, and tests. • Download .NET RIA Services - Microsoft .NET RIA Services simplifies the traditional n-tier application pattern by bringing together the ASP.NET and Silverlight platforms. RIA Services provides a pattern to write application logic that runs on the mid-tier and controls access to data for queries, changes, and custom operations.