I reckon .NET platform is a combination of two major aspects i.e., CLR (Common Language Runtime) and BCLs (Base Class Libraries) which are interdependent on each other. CLR is responsible for performing all the system wide operations such as executing a .NET app , garbage collection and providing security to the code. BCLs are the predefined libraries written in C# language.

        CLR is responsible for executing a .NET App on the client machine using the BCLs. This is where the interdependency between CLR and BCL's comes into picture.

        For instance, imagine that your body is a .NET platform, your brain is CLR, your physical parts like hands are BCLs and whatever the action you perform is an application. Now in your body (.NET platform) your brain (CLR) uses your hands (BCLs) to perform (execute) an action (application) like eating etc., Similar is the functionality in a .NET platform.