Fitness, agility, and balance apply as much to software development as they do to athletic activities. We can admire the movements of a highly skilled dancer, skier, or athlete. Gracefulness comes from wasting no energy on unnecessary tension or balance recovery, so that effort can be focused exactly where it is needed, exactly when it is needed. The expert is continuously making small adjustments to stay aligned and in balance. Agile responses to unexpected changes distinguish the expert from the nonexpert, as their rebalancing adjustments are fluid and subtle and go unnoticed by nonexperts. Injury, pain, distractions, and poor concentration can wreck balance, reducing the expert's ability to respond well in a focused way. Much more effort is required to perform even at a substandard level. A high degree of fitness and practice is needed in order to build the required concentration, balance, agility, and focused power. This, inevitably, is a process of refinement over time, with attention given to more subtle aspects of risk assessment and response as expertise increases. The achievements of athletes have continued to improve over time, sometimes through changes that break assumptions about the activity or how best to train. Big changes are often met with skepticism but will slowly become accepted as the norm as they prove their worth. When we look at the efforts of most software developers, we see a lot of energy being wasted. In the rush to get software completed, there is often little time to reflect on how to improve the way we do things, how to get that special fitness, balance, and agility that allow us to be graceful in our intellectual efforts in order to achieve inspired results with less effort. We get unbalanced when we have to fix old bugs, losing flow. We often have to speculate about what's needed, and feedback is too slow. Our software becomes less than elegant and is difficult to change, with tensions and stresses building up in us and in our software. This book is intended to help improve your fitness and agility in two areas of software development where we can make huge improvements to current practice. First, improving communication between the people who need the software and the people who develop it, as well as show you how to express the business rules that are at the heart of a software solution. Second, how to use automated testing to provide immediate and effective feedback so we can maintain balance and agility and avoid "injury." The book also questions some common assumptions about the way in which software is developed. But we don't expect that you'll make a big leap of faith: We start with current practice and show how you make small yet effective improvements. Just like the dancer and the athlete, you will have to do more than simply read about how to do this. It is also necessary to practice. Rick Mugridge Ward Cunningham 0321269349P06012005