What is the purpose of abstract classes and when are they used?

[renegade109]

More specifically, say I have classes Animal, Bird, and Parrot...

Parrot "is-a" Bird
and
Bird "is-a" Animal

I am not given any other information and I have to decide which are superclasses, subclasses, abstract, or concrete (may have multiple answers).

I know Animal is a superclass and Parrot is a subclass, but what is class Bird? This confuses me because it's caught in the middle so is it both (subclass of Animal, but superclass of Parrot? Or just a subclass?).

What REALLY confuses me is which ones are abstract or concrete.
I have no idea when/in-what-situations I am supposed to use abstract classes and all the giberish online is not helping me (that and I left my inclass notes on my school computer in the classroom...). What I mean, is that the online FAQ is not in a very "noob-friendly" language and it merely confuses me further.

Could someone please tell me in layman's terms when to use superclasses, subclasses, abstract classes, and concrete classes in the example above?

[Dheeraj Joshi]

Animal class is a super class
Bird class is a child class
Parrot class is a grand child class.

There are certain set of functionalities which are in Animal class need to be there in Parrot. Like breathing.

This link may help you a bit regarding abstract classes.

If you have any other questions please post back.

This is a good tutorial to start with.

Regards
Dheeraj Joshi