XNA Framework
The XNA Framework is based on the .NET Framework 2.0. It has been designed with an extensive set of class libraries, specific to game development exercises, to promote maximal code reuse across target platforms. It will also include a version of the Common Language Runtime, which is optimized for gaming requirements, to provide a managed execution environment to the XNA games. The runtime will be available for Windows XP, Windows Vista and the Xbox 360. Since XNA games will be written for the runtime, XNA games will run on any platform supporting the XNA framework, with minimal or no modification. Games targeting the XNA framework can be written using the C# language.
The XNA Framework thus encapsulates low-level technological details involved in coding a game, making sure that the framework itself takes care of the difference between platforms when games are ported from one compatible platform to another, and thereby allowing game developers to focus more on the content and gaming experience. The XNA framework will integrate with a number of tools, such as XACT [1] etc., to aid in content creation, as well. These tools can help author the visuals or sounds in the game, and model characters with life-like dynamism.
Currently games on the XNA framework can only be written using Microsoft's own C# programming language. XNA FAQ