The ability to extend classes through inheritance is truly the foundation on which complex yet manageable programs are built in .NET. And they are not overly complex either. Classes are simple containers for their members, and the variety and complexity of the available members is not that great. So it's really amazing that you can write almost any type of program, and implement any number of features, using these simple foundational tools. Oh yeah, the Visual Basic language helps, too.
As we add code to the Library Project throughout this book, you will become more and more familiar with classes, structures, modules, and their members. And while you'll never remember whether ByRef or ByVal is the default parameter-passing mechanism for methods, you will add properties, methods, events, fields, and other types to classes like you were born with the ability.