This book is full of practical, hands-on re-engineering knowledge and expertise presented in a form that makes it easy to understand and use. This book documents a catalogue of patterns for reverse engineering and reengineering legacy systems. The subject matter is presented in a lucid and succinct style so that even those who do not have a prerequisite knowledge of the subject can easily understand it. This book is addressed mainly to practitioners who need to reengineer. The patterns in this book help everyone who is concerned with using reengineering to guide their work.