For other uses, including audio feedback, see Feedback (disambiguation).
Feedback is (generally) information about actions.
In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input. Often this is done intentionally, in order to control the dynamic behaviour of the system. Feedback is observed or used in various areas dealing with complex systems, such as engineering, architecture, economics, and biology.