Why does the G20 - meeting this year in Brisbane, Australia - exist? And what's it supposed to do? The group is a forum for the governments and central bank governors from 20 major economies. The members include 19 individual countries: Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, South Korea, Mexico, Russia, Saudi Arabia, South Africa, Turkey, the United Kingdom and the United States, plus the European Union.