C# allows the user to inherit one interface into another interface. When a class implements the inherited interface then it must provide the implementation of all the members that are defined within the interface inheritance chain.
Important Points:  

If a class implements an interface, then it is necessary to implement all the method that defined by that interface including the base interface methods. Otherwise, the compiler throws an error.

If both derived interface and base interface declares the same member then the base interface member name is hidden by the derived interface member name.