A "Watt-Hour" (Wh) is a unit of energy that measures how much power is used over time. It is defined as the amount of energy consumed when a device uses one watt of power for one hour. For example, if a light bulb rated at 60 watts is used for one hour, it consumes 60 watt-hours of energy. Watt-hours are commonly used to quantify energy consumption in household appliances and electronic devices. Understanding watt-hours helps consumers manage their energy use and costs, as seen in electricity bills, which often list usage in kilowatt-hours (kWh), where 1 kWh equals 1,000 watt-hours.