A gigawatt (GW) is a unit of electrical power equal to one billion watts or 1,000 megawatts—representing massive amounts of power generation or consumption. For context, a typical large nuclear or coal power plant generates about 1 GW, Canada's total electricity generating capacity is approximately 150 GW, and large hydroelectric dams like those in Quebec or British Columbia may exceed 5 GW capacity. The term gained popular recognition from the "1.21 gigawatts" needed to power time travel in the movie Back to the Future. When discussing energy policy, generation capacity is measured in GW while actual energy production over time is measured in gigawatt-hours (GWh) or terawatt-hours (TWh). Understanding power units helps interpret discussions about electricity systems, renewable energy deployment, and energy policy. Canada's electricity generation mix varies by province, with significant hydroelectric, nuclear, natural gas, and growing renewable capacity.