Objects: Why are they useful?

[eluser]Beren[/eluser]
[quote author="codex" date="1201063122"]Ucant & Wired:

I (think I) understand the concept of objects a bit better. You have a class called Animal, and in this class all functions that make an animal an animal are described. You can create instances of the animal class (objects) to create dog, cat etc etc and have all those properties available. Right? If right I understand ;-)[/quote]

No not entirely, you have a class Animal (that might do things like eat, move etc) and then you would have further classes 'inherited' from that like Cat (does things like meow, purr) and Dog (bark and fetch_ball). Instances are specific cats or dogs, so Fido is an 'instance' of the 'class' Dog (which is a type of class extended from Animal). Likewise Garfield is an instance of a Cat class. An instance is a single 'thing' of a specific 'class'. See?