In this book, we study the control of nonlinear systems, organized into an introduction, five chapters and a conclusion: The first chapter is devoted to a brief review of state models of nonlinear systems, stability theory of nonlinear systems and the various methods of controlling nonlinear systems. In the second chapter, general notions on fuzzy logic are presented, as well as the composition of a fuzzy control system, and the different types of control using fuzzy logic. The third chapter covers the fundamentals of variable-structure control and some basic concepts of sliding-mode theory. The fourth chapter is devoted to the study and synthesis of hybrid fuzzy sliding mode control to solve the problem of stability and reference trajectory tracking for a class of nonlinear systems. In the fifth chapter, the adaptive fuzzy sliding mode control technique is presented. Finally, the conclusion presents the results of this work and the prospects for the future.