What is a watt?
The watt is a unit of power. It is a Newton meter per second, or can be given as a joule per second. We often encounter it in electrical calculations, and it is the unit of power for applications there. The formula for power is given here:
P = I x E
In this expression, the power (P) in watts is equal to the current (I) in amps (or amperes, if you prefer) times the voltage (E) in volts.
The simplest example of a watt would be the amount of power that you would have if you had one volt at one amp of current. Or, to put it another way, 1 volt X 1 Amp=1 Watt. To go further, 12 volts at 1 amp equals 12 watts. This is for direct current measurement.
For AC voltage, it varies in that you would multiply the volts by .707 (AC RMS voltage), then multiply by the amps to get your watts total.