Abstract Class

An abstract class can be defined as parent or the base class only from which child or the derived classes can be generated. As such abstract classes don’t have their objects; objects are only made through the derived class. A derived class that implements all the missing functionality of the abstract class is called a concrete class. Abstract class is a class created as a master structure.
The methods contained in abstract class are called abstract methods; these abstract methods are extended by the concrete classes (subclasses).