OOP addreses one of the real shortcomings of C# and VS.Net--their Visual Basic heritage. Visual Basic was certainly easy to use; slap some controls on a form, add some code to the controls' event handlers, and you had yourself a working program. The problem is, this simplicity encouraged really ugly programs that couldn't be changed or extended. To use a house analogy, you couldn't simply repaint your kitchen. You had to tear it down and build a new one.

That's one of the main reasons why VB developed a reputation as a 'toy' language, and why 'real' programmers turned to Java in droves. It offers much of the simplicity of VB, but it encourages the creation of cohesive, loosely coupled objects that are easily extended, maintained, and reused.

C# has retained almost all of VB's simplicity, with predictable results. C# web sites are full of slapdash apps that whip up a few forms and plug in some code. C# is in real danger of becoming another toy.

And yet, C# offers a rich set of abstaction tools. With these tools, a developer can create real applications, in a fraction of the time required to do it in C++. The same language can be used to build junk, or really elegant applications.

The key to using C# effectively is OOP. The 'Gang of Four' (GoF) design patterns discussed in this book provide proven solutions to common OOP issues. If you understand the GoF patterns, you have a good understanding of OOP. It's that simple. And that's what Cooper sets out to provide.