The .NET Framework class library and the common language runtime.
The .NET Framework class library facilitates types (CTS) that are common to all .NET languages. The common language runtime consists of (class loader) that load the IL code of a program into the runtime, which compiles the IL code into native code, and executes and manage the code to enforce security and type safety, and provide thread support.
.NET Framework Architecture has languages at the top such as VB .NET C#, VJ#, VC++ .NET; developers can develop (using any of above languages) applications such as Windows Forms, Web Form, Windows Services and XML Web Services. Bottom two layers consist of .NET Framework class library and Common Language Runtime. This we are going to understand using this article.