The purpose of this book is to give an exposition of recently adaptive PI/PD/PID control design for nonlinear systems. Since PI/PD/PID control is simple in structure and inexpensive in implementation, it has been undoubtedly the most widely employed controller in industry. In fact, PI/PD/PID controllers are sufficient for many control problems, particularly when process dynamics are benign and the performance requirements are modest. The book focuses on how to design general PI/PD/PID controller with self-tuning gains for different systems, which includes SISO nonlinear system, SISO nonaffine system and MIMO nonlinear system.