Earth Hour is a global event organized by WWF (World Wide Fund for Nature, also known as World Wildlife Fund) and is held on the last Saturday of March annually, asking households and businesses to turn off their non-essential lights and other electrical appliances for one hour to raise awareness towards the need to take action on climate change. Earth hour was conceived by WWF and The Sydney Morning Herald in 2007, when 2.2 million residents of Sydney participated by turning off all non-essential lights.

India along with 92 other countries will observe "lights out" between 8.30 p.m. and 9.30 p.m. Saturday. All government buildings, private banks and ITC hotels will turn off lights during this time. 

" Delhi  was the lead city for Earth Hour 2009 when India joined this global campaign. Several historical buildings, office complexes, Resident Welfare Associations (RWAs), shopping centres and hotels switched off in support, resulting in close to 750 MW power saving in Delhi alone," Dikshit said. 

Bollywood star Abhishek Bachchan, the brand ambassador of this initiative, also enthused everyone to 'act responsibly'. 

"As responsible citizens of this planet, it is extremely crucial for us to address the colossal problem of climate change through ensuring responsible action and adopting a sustainable way of life... It is time we take a collective pledge to 'switch on' our minds and take one simple step to switch off the lights from 8.30 to 9.30 p.m.," Bachchan said. 

Many people in the country are planning to have candlelight dinners to show their commitment to save power and have some fun at the same time.

World-famous landmarks including the Pyramids, the Eiffel Tower and Beijing's Forbidden City will go dark Saturday as millions turn out the lights for "Earth Hour" , a rolling grassroots movement aimed at fighting climate change.