A gigawatt is a unit of power equal to one billion watts. The word comes from giga, a prefix meaning billion, and watt, named after James Watt, the Scottish inventor who helped develop the steam engine.

To understand how much power a gigawatt represents, start with a single watt: that's about enough to light a small LED. A thousand watts (a kilowatt) might run your microwave. A million watts (a megawatt) could power a small neighborhood. A billion watts (a gigawatt) is the output of a large power plant that could supply electricity to hundreds of thousands of homes.

Nuclear power plants typically generate around one gigawatt of power. The largest solar farms in the world produce around two gigawatts when the sun is shining brightly. When engineers plan how much electricity a city or region needs, they think in gigawatts.

You might recognize the word from Back to the Future, where Doc Brown's time machine needs 1.21 gigawatts to work. In the movie, he exclaims that this requires an enormous bolt of lightning. In reality, while a gigawatt is a tremendous amount of power, large power plants can produce it continuously every day to keep our lights on, our computers running, and our cities humming with energy.