Illustrate the term- Abstracting Out Common Behaviour

Inheritance is not every time recognised during analysis phase of development, thus it is necessary to re-evaluate object model to find common operations among classes. Also during design, new classes and operations can be added. If a set of operations or/and attributes seems to be repeated in two classes, then it indicates that two classes are specialised variation of the exact general class.

When common behaviour is identified, a common super class can be created which implements shared features, leaving only specialized features in derived classes. This transformation of the object model is known as abstracting out a common super class or a common behaviour. 

The creation of an abstract super class also enhances the extensibility of the software product.

Associations are useful for finding access paths among objects in system. During object design itself, we should implement associations.