Common Language Runtime
The Common Language Runtime (CLR) is the virtual machine component of Microsoft's .NET initiative. It is Microsoft's implementation of the Common Language Infrastructure (CLI) standard, which defines an execution environment for program code. The CLR runs a form of byte code called the Microsoft Intermediate Language (MSIL), Microsoft's implementation of the Common Intermediate Language.
Developers using the CLR write code in a high level language such as C# or VB.Net. At compile-time, a .NET compiler converts such code into MSIL (Microsoft Intermediate Language) code. At runtime, the CLR's just-in-time compiler (JIT compiler) converts the MSIL code into code native to the operating system. Alternatively, the MSIL code can be compiled to native code in a separate step prior to runtime. This speeds up all later runs of the software as the MSIL-to-native compilation is no longer necessary.
Although some other implementations of the Common Language Infrastructure run on non-Windows operating systems, the CLR runs on Microsoft Windows operating systems.
Feature of :
Performance improvements.
The ability to easily use components developed in other languages.
Extensible types provided by a class library.
New language features such as inheritance, interfaces, and overloading for object-oriented programming; support for explicit free threading that allows creation of multithreaded, scalable applications; support for structured exception handling and custom attributes.
.NET Framework Class Library
The Base Class Library (BCL) is a library of types and functionalities available to all languages using the .NET Framework. In order to make the programmer's job easier, .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation. It is much larger in scope than standard libraries for most other languages, including C++, and would be comparable in scope to the standard libraries of Java. The BCL is sometimes incorrectly referred to as the Framework Class Library (FCL), which is a superset including the Microsoft.* namespaces.
For example, you can use the .NET Framework to develop the following types of applications and services:
