With the gradual complexity of practical engineering systems, large-scale nonlinear interconnected systems and their control design have become the research focus of relevant scholars. These systems are composed of multiple subsystems coupled together, and the subsystems affect the final output signals by influencing the states of other subsystems. Compared with traditional independent systems, the interconnected systems have significant advantages in the face of increasingly complex task requirements in practical systems. Therefore, designing effective controllers for interconnected systems has more practical significance. In this book, for the interconnected systems with input nonlinearities and other constrains, their control design problems are studied. For such nonlinear systems including nonlinear interconnected systems, they will be subject to various constrains: system faults, time delays, input nonlinearities, attacks, power uncertainties, and so on. The input nonlinearities include dead-zone, sector input nonlinearities and backlash-like hysteresis. Firstly, the survey of nonlinear systems including interconnected nonlinear systems is introduced in this chapter. Then, the research on the systems with the above constrains is also introduced. Further, this chapter formulates several issues investigated in this book. At the same time, their works are described for the chapters in this book, and their relationship is given.