Preface

The goal of Extreme Programming (XP) is outstanding software development. Software can be developed at lower cost, with fewer defects, with higher productivity, and with much higher return on investment. The same teams that are struggling today can achieve these results by careful attention to and refinement of how they work, by pushing ordinary development practices to the extreme.

There are better ways and worse ways to develop software. Good teams are more alike than they are different. No matter how good or bad your team you can always improve. I intend this book as a resource for you as you try to improve.

This book is my personal take on what it is that good software development teams have in common. I've taken things I've done that have worked well and things I've seen done that worked well and distilled them to what I think is their purest, most “extreme” form. What I'm most struck with in this process is the limitations of my own imagination in this effort. Practices that seemed impossibly extreme five years ago, when the first edition of this book was published, are now common. Five years from now the practices in this book will probably seem conservative.

If I only talked about what good teams do I would be missing the point. There are legitimate differences between outstanding teams' actions based on the context in which they work. Looking below the surface, where their activities become ripples in the river hinting at shapes below, there is an intellectual and intuitive substrate to software development excellence that I have also tried to distill and document.

Critics of the first edition have complained that it tries to force them to program in a certain way. Aside from the absurdity of me being able to control anyone else's behavior, I'm embarrassed to say that was my intention. Relinquishing the illusion of control of other people's behavior and acknowledging each individual's responsibility for his or her own choices, in this edition I have tried to rephrase my message in a positive, inclusive way. I present proven practices you can add to your bag of tricks.

• No matter the circumstance you can always improve.

• You can always start improving with yourself.

• You can always start improving today.

Acknowledgments

I would like to thank my most excellent group of reviewers, each of whom spent considerable time reading and commenting on the manuscript: Francesco Cirillo, Steve McConnell, Mike Cohn, David Anderson, Joshua Kerievsky, Beth Andres-Beck, and Bill Wake. The Silicon Valley Patterns Group also provided valuable feedback on drafts: Chris Lopez, John Parello, Phil Goodwin, Dave Smith, Keith Ray, Russ Rufer, Mark Taylor, Sudarsan Piduri, Tracy Bialik, Jan Chong, Rituraj Kirti, Carlos Mc Evilly, Bill Venners, Wayne Vucenic, Raj Baskaran, Tim Huske, Patrick Manion, Jeffrey Miller, and Andrew Chase. Thanks to the production staff at Pearson: Julie Nahil, Kim Arney Mulcahy, and Michelle Vincenti. Paul Petralia, my editor, saw me through difficult times with humor and understanding. He taught me lessons in the value of relationships. Erich Gamma, my pair programming partner, provided conversation and feedback. The owners and staff of Bluestone Bakery and Cafe kept the hot chocolate and broadband flowing. Joëlle Andres-Beck edited copy and collected garbage. All of my children; Lincoln, Lindsey, Forrest, and Joëlle; spent many hours at Bluestone while we edited. Gunjan Doshi provided thought-provoking questions.

Finally, I cannot possibly give sufficient thanks to my wife, developmental editor, friend, and intellectual colleague Cynthia Andres.