A kilowatt-hour (kWh) is a unit of energy that measures how much electricity is used over time. It represents the amount of energy consumed when a device with a power rating of one kilowatt operates for one hour. For example, if you run a 1,000-watt appliance for one hour, it will use one kWh of electricity. Electric companies often use kilowatt-hours to bill customers for their energy consumption. By tracking how many kWh a household or business uses, they can calculate the total cost of electricity. Understanding kWh helps consumers manage their energy use and reduce costs.