In mathmatics and physics, chaos theory describes the behavior of certain nonlinear dynamical systems that under certain conditions exhibits dynamics that are sensitive to initial conditions (popularly referred to as the butterfly effect). As a result of this sensitivity, the behaviour of chaotic systems appear to be random because of an exponential growth of errors in the initial conditions.

This happens even though these systems are deterministic in the sense that their future dynamics are well defined by their initial conditions, and there are no random elements involved.