watts

Watts is the SI unit of power, defined as one joule per second. It is named after James Watt, the 18th‑century Scottish inventor who made practical improvements to the steam engine. The unit was adopted for use in the International System of Units in the late 19th century, and its symbol is W. It is used to quantify the rate of energy transfer, including electrical, mechanical, and thermal power. Common multiples include kilowatt (kW), megawatt (MW), and gigawatt (GW).

In electrical contexts, power is P = VI, where V is voltage and I is current; this reduces to 1 W when 1 volt is applied across 1 ampere of current. A watt can also describe radiant flux in optics, or mechanical power in rotating machinery. Prefixed multiples allow expressing very large or small powers, and other watt derivatives include deciwatt and microwatt.

Watts may also refer to people with the surname Watts, such as Isaac Watts (1674–1748), an English hymn writer, and Alan Watts (1915–1973), a British‑American philosopher and writer. In Los Angeles County, Watts refers to a neighborhood in the city of Los Angeles, notable for its social and cultural history, including the Watts Riots of 1965.