Traders at a night market on Hanoi’s Hang Dau street switch off the lights during Earth Hour 2022. (Photo: VNA)

Started in 2007 by the World Wildlife Fund (WWF) and partners as a symbolic lights-out event in Sydney to raise awareness of climate change, Earth Hour is now one of the world's largest grassroots movements for the environment. 

Held every year on the last Saturday of March, Earth Hour engages supporters in more than 190 countries and territories, all taking action to ensure a brighter future for people and the planet. 

Vietnam first joined the drive in 2009. Last year, the country saved 353,000 kWh of electricity.