A dehumidifier is composed of compressor, heat exchanger, fan, water tank, outer body and controller. It takes moisture out of the air by sucking moist air on one side, moving that air over some ice cold tubes that cause the moisture to collect on these tubes and then drip into a tank or tube, and pushing the dry air out the other. This dry air then mixes with the moist air making it a little drier, which in turn is pulled into the unit to become drier over and over again.