The .NET Framework is Microsoft's Managed Code programming model for building applications on Windows clients, servers, and mobile or embedded devices. Microsoft's .NET Framework is a software technology that is available with several Microsoft Windows operating systems.

The Microsoft .Net Framework is a platform that provides tools and technologies needed to build Networked Applications as well as Distributed Web Services and Web Applications. The .Net Framework provides the necessary compile time and run-time foundation to build and run any language that conforms to the Common Language Specification (CLS). The main two components of .Net Framework are Common Language Runtime (CLR) and .Net Framework Class Library (FCL).

The Common Language Runtime (CLR) is the runtime environment of the .Net Framework, which executes and manages all running code like a Virtual Machine. The .Net Framework Class Library (FCL) is a huge collection of language-independent and type-safe reusable classes. The .Net Framework Class Libraries (FCL) is arranged into a logical grouping according to their functionality and usability is called Namespaces.

Microsoft .Net Languages Source Code is compiled into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) is a CPU independent set of instructions that can be converted to the native code. Metadata also created in the course of compile time with Microsoft Intermediate Language (MSIL) and stored it with the compiled code. Metadata is completely self-describing. Metadata is stored in a file called Manifest, and it contains information about the members, types, references and all the other data that the Common Language Runtime (CLR) needs for execution.

The Common Language Runtime (CLR) uses metadata to locate and load classes, generate native code, provide security, and execute Managed Code. Both Microsoft Intermediate Language (MSIL) and Metadata assembled together are known as Portable Executable (PE) file.

During the runtime the Common Language Runtime (CLR)'s Just In Time (JIT) compiler converts the Microsoft Intermediate Language (MSIL) code into native code to the Operating System. The native code is Operating System independent and this code is known as Managed Code, that is, the language's functionality is managed by the .NET Framework. The Common Language Runtime (CLR) provides various Just in Time (JIT) compilers, and each works on a different architecture depends on Operating Systems, that mean the same Microsoft Intermediate Language (MSIL) can be executed on different Operating Systems.