.NET Framework, is a software framework developed by Microsoft. It primarily runs on Microsoft Windows and includes a large class library known as Framework Class Library abbreviated as FCL. Also, it provides language inter operability in several programming languages across Programs written for .NET Framework execute in a software environment (as contrasted to hardware environment), known as Common Language Runtime (CLR), an application virtual machine that provides services such as security, memory management, and exception handling. FCL and CLR together constitute .NET Framework. Interoperability means each language can use code written in other languages.