This is a book about Extreme Programming (XP). XP is a lightweight methodology for small-to-medium-sized teams developing software in the face of vague or rapidly changing requirements. This book is intended to help you decide if XP is for you.
To some folks, XP seems like just good common sense. So why the "extreme" in the name? XP takes commonsense principles and practices to extreme levels.
If code reviews are good, we'll review code all the time (pair programming).
If testing is good, everybody will test all the time (unit testing), even the customers (functional testing).
If design is good, we'll make it part of everybody's daily business (refactoring).
If simplicity is good, we'll always leave the system with the simplest design that ...