ELI5: Explain Like I'm 5

Nonlinear system

Nonlinear systems are types of systems where the output does not directly depend on the input. Instead, the output from the system is based on how the input changes over time. For example, when you put a ball on the top of a hill, the ball will roll down. The ball's motion will depend on the shape and size of the hill and it won't always go in the same direction. That is a nonlinear system.