Common Language Runtime

      The .NET Framework provides a run-time environment called the common language runtime, which runs the code and provides services that make the development process easier.

Code that you develop with a language compiler that targets the runtime is called managed code; it benefits from features such as cross-language integration, cross-language exception handling, enhanced security, versioning and deployment support, a simplified model for component interaction, and debugging and profiling services.

      The runtime automatically handles object layout and manages references to objects, releasing them when they are no longer being used. Objects whose lifetimes are managed in this way are called managed data. Garbage collection eliminates memory leaks as well as some other common programming errors. If your code is managed, you can use managed data, unmanaged data, or both managed and unmanaged data in your .NET Framework application. Because language compilers supply their own types, such as primitive types, you might not always know (or need to know) whether your data is being managed.

      The common language runtime makes it easy to design components and applications whose objects interact across languages. Objects written in different languages can communicate with each other, and their behaviours can be tightly integrated

       For an instance, you can define a class and then use a different language to derive a class from your original class or call a method on the original class. You can also pass an instance of a class to a method of a class written in a different language. This cross-language integration is possible because language compilers and tools that target the runtime use a common type system defined by the runtime, and they follow the runtime's rules for defining new types, as well as for creating, using, persisting, and binding to types.

CLR Provide following features:

• Performance improvements.
• The ability to easily use components developed in other languages.
• Extensible types provided by a class library.
• 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.
• Support for custom attributes.
• Garbage collection.
• Use of delegates instead of function pointers for increased type safety and security. For more information about delegates