Feedback

A circuit within a system or subsystem, electronic, mechanical or social, in which a portion of the output is connected back to the input. The information signal may be shaped mechanically or electronically or carried remotely by a communications system. In a cyclic system, feedback exists when the output of one cycle forms a portion of the input to the next, either deliberately or by accident. The familiar screeching of a public address system in which the microphone is too close to the speaker serves as an example of feedback. Also, pertinent is a socio-political system in which the policies of politicians in power are influenced, for better or worse, by public opinion.