Earth Hour was created by the World Wide Fund for Nature (W.W.F.) and is held annually, encouraging individuals, communities, and businesses to turn off non-essential electric lights, for one hour, from 8:30 p.m. to 9:30 p.m, as a symbol of commitment to the planet. Spend one hour tonight "unplugged" and under the stars to save our earth!
Original source can be found here.