A watt is a unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m²⋅s⁻³. It is used to quantify the rate of energy transfer. Power is a measure of the rate at which energy flows, and in electrical systems, it is measured in watts (W) . Watts are like miles-per-hour in the electrical world, they tell you how fast the electrons are speeding down the highway. One watt is equivalent to electricity flowing at a rate of one joule per second in the metric system, which is also equivalent to 3.4 Btus per hour. The watt is named after James Watt, an 18th-century Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own steam engine in 1776.