Common Language Runtime

The Common Language Runtime (CLR) is the virtual machine in the .NET Framework. It sits on top of the Windows operating system (Windows XP, Windows Vista, Windows Server 2008, and so on). A .NET application is compiled into a bytecode format known as MSIL

(Microsoft Intermediate Language). During execution, the CLR JIT ( just - in - time)

compiles the bytecode into the processor ’ s native code and executes the application. Alternatively, MSIL code can be precompiled into native code so that JIT compiling is no longer needed; that speeds up the execution time of your application.

The CLR also provides the following services:
Memory management/garbage collection
Thread management
Exception handling
Security

.NET developers write applications using a .NET language such as C#, VB.NET, or C++. The MSIL bytecode allows .NET applications to be portable (at least theoretically) to other platforms because the application is compiled to native code only during runtime.