CLR stands for Common Language Runtime, which is a core component of the .NET Framework that manages the execution and lifecycle of all .NET applications. When a .NET application is compiled, it generates an intermediate language code called Common Intermediate Language (CIL), which is then translated into machine code by the CLR. The CLR provides various services, including automatic memory management, exception handling, security, and type safety. It also allows programs written in different .NET languages to easily use libraries written in another .NET language. All programs written for the .NET Framework, regardless of programming language, are executed in the CLR.