In the analysis of dynamical systems, noise is usually considered a nuisance. Unfortunately many natural systems are intrinsically nonlinear and operate in noisy environments.
Examples are easy to find.
They range from weather systems, to chemical reactions, to electronic circuits to neurons. In certain nonlinear forced dynamical systems the presence of noise can enhance the detection of weak signals. This constructive role, via a mechanism called stochastic resonance, is now known to occur in a wide range of physical systems. Stochastic resonance as a physical process is now firmly recognized as a genuine and common physical phenomenon. In 1981-2 a group of European scientists described the general dynamical mechanism in which small periodic perturbation could be amplified by large environmental fluctuations.