While the first publication of the Gang of Four's Design Patterns: Elements of Reusable Object-Oriented Software was in October of 1994, it has only been in the last 6 or 7 years that I started paying attention to design patterns. Like most experienced developers, when I first started reading about design patterns, I recognized a lot of the patterns because I had already been using them without realizing what they were. I would have to say that in the past 6 or 7 years since I first read about design patterns, I did not write a serious application without using at least one of the Gang of Four's design patterns. I will tell you that I am definitely not a design pattern zealot, and actually, if I get into a conversation about design patterns, there is usually only a couple that I can name without having to look them up, but one thing that I do remember is the concepts of the major patterns and the problems they are written to solve. This way,...