What is the difference between `private` and `protected` members in C++ classes? I understand from best practice conventions that variables and functions which are not called outside the class should be made `private`—but looking at my MFC project, MFC seems to favor `protected`. What's the difference and which should I use?

In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), `public`, `protected` and `private`, while making `class` and `interface` and dealing with inheritance?