A watt is a unit of power that measures the rate at which energy is used or produced. It is defined as one joule per second and is commonly used to quantify the output of engines and the power consumption of electrical devices. For example, a light bulb rated at 60 watts consumes 60 joules of energy every second. The watt is named after the Scottish inventor James Watt, who made significant improvements to the steam engine in the 18th century. In practical terms, watts help consumers understand how much electricity they are using, which can influence energy bills and efficiency choices.