Nonlinear systems is a research area that deals with systems in which the output is not directly proportional to the input, leading to complex and often unpredictable behavior. These systems often exhibit phenomena such as chaos, bifurcation, and sensitivity to initial conditions. Researchers in this field study the dynamics and behavior of these systems, developing mathematical models and tools to analyze and predict their behavior. Nonlinear systems have applications in a wide range of fields, including physics, engineering, biology, and economics.