Give an example of Object Representation 

For illustration, consider the implementation of a social security number within an employee object that is shown in Figure. The social security number attribute could be implemented as a string, an integer or as an association to a social security number object, that itself can contain whether an integer or a string. Defining a new class is more flexible, but often introduces needless indirection. It is suggested that new classes must not be defined unless there is a definite requirement.

Figure: Alternative representations for an attribute