Define access privileges in C++.You have access privileges in C++ such as public, protected and private that helps in encapsulation of data at various level.
If data are declared as private in a class then it is accessible by the member functions of the class where they are declared. The private member functions can be accessed only by the members of the class. By default, any member of the class is considered as private by the C++ compiler, if no specifier is declared for the member.
The member functions with public access specifier can be accessed outside of the class. This kind of members is accessed by creating instance of the class.
Protected members are accessible by the class itself and it's sub-classes. The members with protected specifier act exactly like private as long as they are referenced within the class or from the instance of the class. This specifier specially used when you need to use inheritance facility of C++. The protected members become private of a child class in case of private inheritance, public in case of public inheritance, and stay protected in case of protected inheritance.