The SI unit of power is the watt (W). The Watt is named after the Scottish engineer James Watt, who made significant contributions to the development of the steam engine.

In physics, power is defined as the rate at which work is done or the rate at which energy is transferred or converted. More precisely, one watt is defined as one joule of energy transferred or converted per second.

Mathematically, the watt can be expressed as:

1 watt (W) = 1 joule (J)/1 second (s)

In practical terms, watt is a unit that measures how quickly or how much energy is used or produced per unit of time. It is widely used in various fields, including physics, engineering, and everyday life. For example, it is used to rate the power output of electrical devices, the performance of engines, and the consumption of electrical appliances.