We all change our code, and most of us change other people’s code. Since Visual Basic became the most popular tool for creating applications for Windows some time ago, the software development life cycle has changed for good. Visual Basic programs are not analyzed, designed, and coded in an ordered, sequential fashion. All the traditional phases intermingle because Visual Basic is used for everything from prototyping to analyzing requirements, and the code is rapidly modified thereafter. The tool’s productivity makes this route irresistible, but the downside is that it becomes difficult to prevent your code from degenerating when you continually revisit it. Extensible code is code that can be easily enhanced. The use of classes is key to achieving this.