The technique of deriving a new class from an old one is called inheritance. The old class is referred to as base class and the new class is referred to as derived class or subclass. Inheritance concept allows programmers to define a class in terms of another class, which makes creating and maintaining application easier. When writing a new class, instead of writing new data member and member functions all over again, programmers can make a bonding of the new class with the old one that the new class should inherit the members of the existing class. A class can get derived from one or more classes, which means it can inherit data and functions from multiple base classes.