Watt is a unit of power. It’s defined as joules per second, where joules is a unit of energy. Basically, it’s the speed of energy transfer.
Watt hour basically means “if i’m transferring at *x* watts, how much energy was used in an hour”. It’s like saying MPH hour: “if I’m traveling at *x* mph, how far did I travel in an hour”. So, watt hours is just another unit of energy, just like joules.
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