Earth Hour is an annual campaign organised by the World Wildlife Fund (WWF) to promote environmental awareness.
People around the world simultaneously turn off lights, electric appliances and facade lighting on iconic buildings, for one hour.
Earth Hour is the most widespread campaign in human history. In 2018, over 2 billion people from 188 countries took part in the event, including the residents of 170 Russian cities.
The Moscow Kremlin joined the campaign in 2013 by decision of Vladimir Putin.