Refrigerators are usually put into demo mode when they are being displayed but are not in use, such as in an appliance sales showroom. Demo mode, also called exhibition mode, is used primarily to conserve energy.
Demo mode typically enables certain functions but keeps cooling functions off so that energy is not wasted in keeping the fridge cool unnecessarily. This can save a lot of energy from being wasted, especially since refrigerators that are displayed on a sales floor tend to have their doors opened often.
In a home setting, demo mode is not desirable, as it does not allow the appliance to keep food cool.