What is .NET / .NET Framework? 

It is a Framework in which Windows applications might be developed and run. The Microsoft .NET Framework is a platform for building, deploying, and running Web Services and applications. It provides a highly productive, standards-based, multi-language environment for integrating existing investments with next-generation applications and services as well as the agility to solve the challenges of deployment and operation of Internet-scale applications. The .NET Framework having of three major parts: the common language runtime, a hierarchical set of unified class libraries, and a componentized version of Active Server Pages called ASP.NET. The .NET Framework provides a new programming model and rich set of classes designed to simplify application development for Windows, the Web, and mobile devices. It gives full support for XML Web services, have robust security features, and delivers new levels of programming power. The .NET Framework is used by all Microsoft languages including Visual C#, Visual J#, and Visual C++.