Earth Hour is a worldwide event organized by the World Wide Fund for Nature (WWF) and held towards the end of March annually, encouraging households and businesses to turn off their non-essential lights for one hour to raise awareness about the need to take action on climate change.

Based on an idea successfully executed in Thailand in 2005, it was pioneered by WWF Australia and the Sydney Morning Herald in 2007, and achieved worldwide participation in 2008.

Earth Hour 2013 will be held on March 23, 2013 from 8:30 p.m. to 9:30 p.m. during participants' local time. Hundreds of millions of people will turn off their lights for one hour, on the same night, all across the world in a huge, symbolic show of support.