OOP Explanation

I need some insight, not just knowing the facts.
The 3 areas of OOP are Inheritance, Polymorphism and Encapsulation.

Now, Polymorphism can be applied in 3 ways: By inheriting, by abstracting (abstract classes) and by interfacing (interface class)

What I need to *understand* what is really the difference between abstract and interface classes. What make you use the one above the other?

I'm preparing a short 3-5 minutes "speech" on the question "Define OOP", but don't want to read my answer like a moron. I like to know exactly what i am talking about.

WIKI has a pretty good definition. They use ABSTRACT and PARAMETRIC.

http://en.wikipedia.org/wiki/Polymor...ter_science%29

no hell..gimme some simpler explanation..busy with a lot of stuff, and got to finish tonight :blush:

This is pretty good, but aimed at Java
http://atomicobject.com/training/tra...ymorphism.page
or this for vb.net
http://www.startvbdotnet.com/oop/polymorphism.aspx
and simply stated
http://homepages.unl.ac.uk/~chalkp/p...ymorphism.html

I can't believe it.

I never went further (at least not to gain insight) and the first single question was "What is the difference between an abstract and interface class"

The first, I'm telling ya. So kinda messed up. But it's ok. I did not like the "environment" and the "feel" around there. Rather stay crammed at a small desk at M$ for now then. :D