CLR

Common Language Runtime is the execution engine for .NET Framework applications. It provides a number of services, including the following.Code management (loading and execution), Application memory isolation, Verification of type safety, Conversion of IL to native code , Access to metadata (enhanced type information), Managing memory for managed objects, Enforcement of code access security, Exception handling, including cross-language exceptions, Interoperation between managed code, COM objects, and pre-existing DLLs (unmanaged code and data), Automation of object layout, Support for developer services (profiling, debugging, and so on)