The Common Language Runtime (CLR) is an Execution Environment. It works as a layer between Operating Systems and the applications written in .Net languages that conforms to the Common Language Specification (CLS). The main function of Common Language Runtime (CLR) is to convert the Managed Code into native code and then execute the Program. The Managed Code compiled only when it needed, that is it converts the appropriate instructions when each function is called. The Common Language Runtime (CLR)’s Just In Time (JIT) compilation converts Intermediate Language (MSIL) to native code on demand at application run time. During the execution of the program, the Common Language Runtime (CLR) manages memory, Thread execution, Garbage Collection (GC), Exception Handling, Common Type System (CTS), code safety verifications, and other system services.