What Does Microsoft XNA Mean?
Microsoft XNA is a set of tools provided by Microsoft for video game development and video game management. Provided with a managed runtime environment by Microsoft, Microsoft XNA is based on the .NET framework. Microsoft XNA is targeted for lightweight games running on multiple Microsoft platforms. XNA is not currently under active development and is not supported by some of Microsoft's platforms.
Techopedia Explains Microsoft XNA
Considered as the .NET analog of Direct X, Microsoft XNA is freeware. It is the basic platform for Xbox Live Indie Games. XNA was introduced in 2004 and a Community Technology Preview of XNA Build was provided in 2006. The XNA framework ensures low-level technology changes are also carried on along with the development of the game, which makes the framework itself the difference between the platforms where the games are ported.
Tools such as a cross-platform audio creation tool and a number of other tools are integrated into the XNA framework. These tools along with the XNA framework support both 2-D and 3-D game development. For game developers, the XNA framework provides the right tools for focusing on both gaming and a content-rich experience. Games developed with XNA can be distributed with Windows Phone or Xbox Live Indie Games if there is a license agreement between the developer and Microsoft.
Although XNA is not actively developed, MonoGame, which is freeware cross-platform version of the XNA programming interface, is still actively developed.