A kilowatt-hour (kWh) is a unit of energy commonly used to measure electricity consumption. It represents the amount of energy used when a 1-kilowatt (1,000 watts) device runs continuously for one hour. For example, if you have a 100-watt light bulb and it's turned on for 10 hours, it will use 1 kWh of energy (100 watts x 10 hours = 1,000 watt-hours = 1 kWh). The kWh is the standard unit for which you are billed on your electricity statement.