CLR (Common Language Runtime) mainly has the following common responsibilities:
-CLR's JIT (Just-in-Time) compiler is responsible for execution of the IL (Intermediate Language) code at the developer end while he is developing the .NET apps as well as at the client end when the .NET app is deployed.
-CLR provides automated memory management using Garbage collection. Due to this .NET memory management is isolated from .NET app developer i.e., CLR's garbage collector (GC) takes the responsibility in allocation as well as deallocation of memory for the created objects and there is no role of .NET developer in this activity(allocation and deallocation of memory).
-CLR's Common Type System (CTS) is responsible for maintaining the cross platform support for various types (data types) of various .NET compatible languages.
-CLR's Exception Manager is responsible for runtime error handling (Exception handling).
These are some common responsibilities os CLR. There are even some other responsibilities for CLR that are not discussed above, but will be discussed later.