This book systematically investigates and addresses constrained nonlinear control problem for systems under various conditions, such as input saturation, prescribed performance, communication constraints, actuator faults, time delay, unknown control directions, etc. Throughout the chapters, we propose a variety of control strategies tailored to specific single constraint or multiple constraints. In additional to ensuring the stability and robustness of the closed-loop systems, the proposed control strategies aim to further improve the tracking performance of the controlled systems especially under multiple constraints.