The Group of Eight (G8, and formerly the (G6) or Group of Six) is an international forum for the governments of eight nations: Canada, France, Germany, Italy, Japan, Russia, the United Kingdom, and the United States; in addition, the EU is represented within the G8, but cannot host or chair. The G8 can refer to the member states or to the annual summit meeting of the G8 heads of government. The former term G6 is now frequently applied to the six most populous countries within the European Union (see G6 (EU)). G8 ministers also meet throughout the year, such as the G7/8 finance ministers (who meet four times a year), G8 foreign ministers or G8 environment ministers.

Each calendar year, the responsibility of hosting the G8 rotates through the member states in the following order: France, United States, United Kingdom, Russia, Germany, Japan, Italy and Canada. The holder of the presidency sets the agenda, hosts the summit for that year and determines which ministerial meetings will take place. Lately, both France and the United Kingdom have expressed a desire to expand the group and include five developing countries, referred to as the Outreach Five (O5) or the Plus Five: Brazil, China, India, Mexico and South Africa. These countries have participated as guests in previous meetings, which are sometimes called G8+5. Recently, France and Germany are lobbying to include Egypt to the Outreach Five (O5) and expand the G8 to G14.