ABSTRACTION

Abstraction considering their important characteristics and ignore all specific instance. Abstraction not  having specific instance it will represent common facts. Abstract classes are something in the middle between classes and interfaces. They can define ordinary methods and abstract methods.

Eg:  inside class room we can have students.when we going to implement classes here we using one class called student.Which will contain common instance like student name,student id, student registration number & etc.but we never going to create class under each & every student name n his details .

This abstract classes will not contain individual specific  data of particular object.