The aim of this chapter is to teach you different methods of catching bugs during Visual Basic 5 program development and unit testing, before they can reach the master source files. As programmers, we are in a unique position. First, we can learn enough about bugs and their causes to eliminate large classes of them from our programs during initial development. Second, we are probably the only people who have sufficient knowledge of the internal workings of our programs to unit-test them effectively and thereby identify and remove many bugs before they ever reach our testers and users. Developers tend to be highly creative and imaginative people. The challenge is to impose a certain discipline over that talent in order to attack the bug infestation at its very source. Success in meeting this challenge will give us increased user confidence, less user support calls and complaints, shorter product development times, lower maintenance costs, shorter maintenance backlogs, and increased developer confidence—not to mention an ability to tamper with the reality of those developers who think that a zero-defect attitude to writing code is nonproductive.