The efficient functioning of modern society depends on the smooth operation of many complex systems including transport and communication systems, manufacturing and processing plants, utilities, hospitals and banks. Such systems are unreliable because they degrade with age and/or usage and fail when no longer capable of delivering the products/services. The consequences of a failed complex system can be dramatic (e.g. economic losses). These failures can be controlled by preventive maintenance actions. Advances in the understanding of the physics of failure, and in the technologies used to combat this failure have resulted in a vast literature on this topic. This book is the first to integrate this literature with chapters on a particular aspect of maintenance written by internationally-renowned researchers and practitioners. This book will interest maintenance engineers and managers in industry as well as researchers and graduate students in maintenance, industrial engineering and applied mathematics.