Power is the rate at which work is done, or the rate of transfer of energy. The faster a machine can do work, the most powerful it is.

The SI unit of power is joule per second (J/s). This unit is given a name watt (W).

1 W = 1 J/s

Since watt is a small unit, we use the kilowatt (kW) and the megawatt (MW).

1kW = 1000 W = 10³ W
1 MW = 1000000 W = 10⁶ W

There was another unit of power called the horse power (hp). 1 hp = 746 Watt