The next layer up in the framework is called the .NET Class Framework also referred
as .NET base class library. The .NET Class Framework consists of several thousand
type definitions, where each type exposes some functionality. All in all, the CLR and
the .NET Class Framework allow developers to build the following kinds of
applications:

• Web Services. Components that can be accessed over the Internet very easily.

• Web Forms. HTML based applications (Web Sites).

• Windows Forms. Rich Windows GUI applications. Windows form applications can
take advantage of controls, mouse and keyboard events and can talk directly to
the underlying OS.

• Windows Console Applications. Compilers, utilities and tools are typically
implemented as console applications.

• Windows Services. It is possible to build service applications controllable via the
Windows Service Control Manager (SCM) using the .NET Framework.

• Component Library. .NET Framework allows you to build stand-alone components
(types) that may be easily incorporated into any of the above mentioned
application types.

The Common Language Runtime (CLR)........

At the base is the CLR. It is considered as the heart of the .NET framework. .NET
applications are compiled to a common language known as Microsoft Intermediate
Language or “IL”. The CLR, then, handles the compiling the IL to machine language,
at which point the program is executed.
The CLR environment is also referred to as a managed environment, in which
common services, such as garbage collection and security, are automatically
provided.
More information on CLR is available at