The G20 is made up of 19 member states and the European Union. There are also guest members and a selected few countries invited to the event.
The primary focus for the Hamburg edition will be economic governance but the theme of the summit varies from year to year.
Past themes have centred around clean energy, demographic changes, reform of monetary institutions and the economic down turn of 2008.
Chief executives of several international forums and institutions, such as the IMF and the World Bank, are also invited.
G20 2017 also hosts the leaders from the following nations: Azerbijan, Benin, Brunei, Cambodia, Chad, Chile, Colombia, Egypt, Equatorial Guinea, Ethiopia, Guinea, Kazakhstan, Laos, Malawai, Malaysia, Mauritiana, Myanmar, the Netherlands, New Zealand, Nigeria, Norway, the Phillipines, Poland, Senegal, Singapore, Spain, Switzerland, Thailand, the United Arab Emirates, Vietnam and Zimbabwe.
|What is the G20? [Al Jazeera]|
Source: Al Jazeera and news agencies