Plan. Do. Check. Act. Four simple words that together form a powerful management technique for improving processes, activities, and organisations. We wrote this book to help readers understand and apply the PDCA (Plan, Do, Check, Act) method. It is a model that we have used successfully with clients around the world, helping deliver sustainable performance improvement and shareholder value. The concepts and theory behind the method appear simple and straightforward, but we found that most of the literature on the subject is complicated, overblown, and dull. So, we decided to write this book. We have set out to bring the PDCA method to life, using clear language, simple concepts, and examples from our own experience. We hope that, after reading this book, you will be able to apply the PDCA method to your work, as well as other areas of your life, because the concepts and approach are universally applicable. We do not pretend to cover everything there is to know about the subject, but we hope that this book is the start of your experience of understanding and using the PDCA method to make a difference to everything you do.