An analog signal is an incessant signal for which, the time differing aspect of the signal is a depiction of some other time differing quantity. It varies from digital signals in terms of tiny, meaningful fluctuations in the signal. An analog signal utilizes some feature of the medium to communicate the signal's information. An aneroid barometer utilizes revolving position as the signal to communicate pressure information. In electrical terms, the feature that is most frequently utilized is voltage.