Every year, in late March, people and institutions come together to switch off all non-essential lights for sixty minutes at 8.30 p.m. local time. They do this to show their support for the fight against the climate crisis and loss of biodiversity. Millions of people all around the world join in, as do governments, businesses and institutions. By switching off their lights and measuring the reduction in the amount of energy that is being used, people are showing that it is possible to make a difference. 

But Earth Hour is more than one hour without lights, once a year. It's part of a movement of people who are working together all year round to protect the environment.