The CLR converts CIL (Common Intermediate Language) to native code.
The Common Language Runtime (CLR) is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the compiled code is converted into machine instructions that, in turn, are executed by the computer's CPU. The CLR provides additional services including memory management, type safety and exception handling. All programs written for the .NET framework, regardless of programming language, are executed by the CLR. It provides exception handling, garbage collection and thread management. CLR is common to all versions of the .NET framework.
The CLR is Microsoft's implementation of the Virtual Execution System (VES) as defined in the Common Language Infrastructure (CLI) standard, initially developed by Microsoft itself. The Common Language Infrastructure specification is now defined by a public standard.
Overview of the Common Language Runtime release history
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