In recent years, the systems designed to support activity in the fields of banking, health, transportation, space, aeronautics, defense, etc. have become increasingly larger and more complex. With the growing maturity of information and communication technologies, systems have been interconnected within growing networks, yielding new capabilities and services through the combination of system functionalities. This has led to a further increasing complexity that has to be managed in order to take advantage of these system integrations. The book is divided into two parts. The first part addresses the concept and practical illustrations of a “system of systems” and is a multidisciplinary introduction to the notion of a “systems of systems” that is discussed extensively in the current scientific and technical literature. After a critical comparison of the different definitions and a range of various practical illustrations, this part provides answers to key questions such as what a system of systems is and how its complexity can be mastered. The second part, described as “systems-of-systems engineering: methods and tools”, focuses on both engineering and modeling, and standardization issues that are critical to deal with the key steps in systems of systems engineering: namely eliciting stakeholder needs, architecture optimization, integration of constituent systems, qualification, and utilization.