I feel chaos theory still is one of the greatest fields. The study of chaos represents the most complicated steady-state behavior known in dynamical systems. Recent years have seen rapid improvements in integer and fractional-order chaotic systems with engineering applications. Chaos-based applications form an important issue in both science and engineering. Novel chaotic systems have been presented in recent engineering applications. Many studies have been done on the basis of well-known systems with chaotic attractors, including also the Lorenz, the Chua, and the Chen system.