The Common Language Runtime (CLR) is a an Execution Environment . Common Language Runtime (CLR)'s main tasks are to convert the .NET Managed Code to native code , manage running code like a Virtual Machine and also controls the interaction with the Operating System.

Common Language Runtime (CLR) manages Thread executions, Memory Management that is allocation of Objects and Buffers , Garbage Collection (GC) - Clean up the unused Objects and buffers , Exception Handling, Common Type System (CTS) that is all .NET language that conforms to the Common Language Specification (CLS) have the same primitive Data Types, Code safety verifications - code can be verified to ensure type safety, Language integration that is Common Language Runtime (CLR) follow a set of specification called Common Language Specification (CLS) , this will ensure the interoperability between languages, Integrated security and other system services.