The .NET Framework
Microsoft .NET supports not only language independence, but also language integration. This means that you can inherit from classes, catch exceptions, and take advantage of polymorphism across different languages. The .NET Framework makes this possible with a specification called the Common Type System (CTS) that all .NET components must obey. For example, everything in .NET is an object of a specific class that derives from the root class called System.Object. The CTS supports the general concept of classes, interfaces, delegates (which support callbacks), reference types, and value types.
Additionally, .NET includes a Common Language Specification (CLS), which provides a series of basic rules that are required for language integration. The CLS determines the minimum requirements for being a .NET language. Compilers that conform to the CLS create objects that can interoperate with one another. The entire Framework Class Library (FCL) can be used by any language that conforms to the CLS. Complete coverage of the FCL classes is beyond the scope of this book. For more information on these classes, see VB.NET Language in a Nutshell (Roman, Petrusha, and Lomax, O’Reilly).
The .NET Framework sits on top of the operating system, which can be any flavor of Windows from Win 98 forward,[1] and consists of a number of components.
Currently, the .NET Framework consists of:
Four official languages: VB.NET, C#, Managed C++, and JScript .NET
The Common Language Runtime, ...