According to Yahoo Philippines's article Mark Earth Hour 2012, "Earth Hour started in Australia when the World Wildlife Fund (WWF) asked 2.2 million individuals in more than 2,000 businesses in Australia to turn off their lights for one hour. Since then 5,200 cities and towns in 135 countries and territories have responded with a worldwide commitment to a better future."
Reason for this is very self-explanatory. To save energy that is. Since we owned technology as way of life, sometimes it is the technology that owns us! This is to remind everyone that we need to get in touch with our friends and loved not only on Twitter, Facebook and mobile phones but find time to see them in person, hear their voice and feel their presence.