What is inheritance?

Class, the vehicle, which is used to execute object-oriented concepts in C++, has given a new dimension to this idea of reusability. Many vendors now offer libraries of classes. A class library having of data and methods to operate on that data, encapsulated in a class. The source code of these libraries require not be available to modify them. The new dimension of OOP uses a method called inheritance to modify a class to suit one's requirements.  Inheritance means deriving new classes from the old ones. The old class is called the base class or parent class or super class and the class which is derived from this base class is known as derived class or child class or sub class. Deriving a new class from an existing one, permits redefining a member function of the base class and also adding new members to the derived class and this is possible without having the source of the course explanation also.  In other words, a derived class not only inherits all properties of the base class but also has some refinements of its own. The base class remains unchanged in the process. In other words, the derived class "is a "type of base class, but with more details added. For this reason, the relationship among a derived class and its base class is called an "is-a" relationship.