Watt is one of the best-known units for light and electricity. It indicates the power or energy consumption of a device. Technically, power in watts is calculated by dividing the work (in joules) by the time (in seconds).

The word wattage is not formally correct, but is often used in practice to refer to the energy consumption of a lamp or device.

In short: the higher the wattage, the more energy the device consumes or the brighter a lamp can shine.