Earth Hour is a global environmental movement organized by the World Wide Fund for Nature (WWF) and is held annually on the last Saturday of March. Participants are encouraged to turn off non-essential lights and electronics for one hour, from 8:30 to 9:30 PM local time. The event is intended to raise awareness about climate change and the importance of taking action to reduce carbon emissions.

Earth Hour began in 2007 in Sydney, Australia, as a lights-off event in response to concerns about climate change. The event was a success, with over 2 million people participating, and it has since spread to over 180 countries and territories around the world.

Each year, Earth Hour focuses on a different theme related to climate change. Past themes have included:

* 2008: "Climate Change & You"

* 2009: "Change the Way We Live"

* 2010: "Countdown to Copenhagen"

* 2011: "Go Beyond the Hour"

* 2012: "I Will If You Will"

* 2013: "I Am for the Earth"

* 2014: "Break Free"

* 2015: "Be the Solution"

* 2016: "Shine a Light on Climate Action"

* 2017: "Connect2Earth"

* 2018: "Change the Way We Eat"

* 2019: "Protect Our Species"

Earth Hour has been widely recognized for its impact on raising awareness about climate change. The event has also been credited with helping to reduce energy consumption and carbon emissions. In 2017, Earth Hour participants around the world saved an estimated 450 gigawatt-hours of electricity, which is enough to power over 3 million homes for one year.

Earth Hour is a simple but powerful way for individuals to take action on climate change. By turning off our lights for one hour, we can send a message to our leaders that we are committed to fighting climate change. We can also use Earth Hour as an opportunity to learn more about climate change and the actions we can take to reduce our impact on the environment.