Conclusion

Congratulations if you made it this far - hopefully you found the tutorial to be of some use. This tutorial only begins to explain OOP though - There are lots of important concepts such as polymorphism that I just don't have time to write about! I recommend deciding on a language to learn and obtaining any of the following books.

Programming C#
Jesse Liberty
ISBN: 0-596-00489-3
A good introduction to the C# language with a short section on Object Oriented programming at the beginning of the text.

Accelerated C++
Andrew Koenig, Barbara Moo
ISBN: 0-201-70353-X
A great beginners guide to programming in C++.

Learning Java, 2nd Edition
Patrick Niemeyer, Jonathan Knudsen
ISBN: 0-596-00285-8
This is a book I haven't actually read (the book I learned Java from was quite dire) but it seems like an ideal book for a beginner. Almost all of the books from O'Reilly are worth reading.

Design Patterns, Elements of Reusable OO Software
Gamma, Helm, Johnson, Vlissides
ISBN: 0-201-63361-2
Describes Patterns, advanced Object Oriented programming solutions to common problems. You can use this book while learning any of the above languages.

As I said at the start of this tutorial, the best way to learn OOP is by practice - pick up one of the SDKs mentioned in the introduction and start playing today!

Please feel free to contact me with any questions on the tutorial. Good luck!