"G8" can refer to the member states in aggregate 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. 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.
Collectively, the G8 nations comprise 53.0% of global nominal GDP and 42.5% of global GDP (PPP). 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 to include five developing countries, referred to as the Outreach Five (O5) or the Plus Five: Brazil, People's Republic of China, India, Mexico, and South Africa. These countries have participated as guests in previous meetings, which are sometimes called G8+5.
With the G-20 major economies growing in stature since the 2008 Washington summit, world leaders from the group announced at their Pittsburgh summit on September 25, 2009, that the group will replace the G8 as the main economic council of wealthy nations. 
The concept of a forum for the world's major industrialized democracies emerged following the 1973 oil crisis. In 1974, a series of meetings in the library of the White House in Washington, D.C. was known as the "Library Group". This was an informal gathering of senior financial officials from the United States, the United Kingdom, West Germany, Japan and France. In 1975, French President Valéry Giscard d'Estaing invited the heads of government from West Germany, Italy, Japan, the United Kingdom and the United States to a summit in Château de Rambouillet. The six leaders agreed to an annual meeting organized under a rotating presidency, forming the Group of Six (G6). The following year, Canada joined the group at the behest of Germany's Chancellor Helmut Schmidt and U.S. President Gerald Ford and the group became the Group of Seven (G7). The European Union is represented by the President of the European Commission and the leader of the country that holds the Presidency of the Council of the European Union. The President of the European Commission has attended all meetings since it was first invited by the United Kingdom in 1977 and the Council President now also regularly attends.
Following 1994's G7 summit in Naples, Russian officials held separate meetings with leaders of the G7 after the group's summits. This informal arrangement was dubbed the Political 8 (P8) – or, colloquially, the G7+1. At the invitation of Prime Minister of the United Kingdom Tony Blair and President of the United States Bill Clinton, Russia formally joined the group in 1997, resulting in the Group of Eight, or G8.
By design, the G8 deliberately lacks an administrative structure like those for international organizations, such as the United Nations or the World Bank. The group does not have a permanent secretariat, or offices for its members.
The presidency of the group rotates annually among the member countries, with each new term beginning on 1 January of the year. The country holding the presidency is responsible for planning and hosting a series of ministerial-level meetings, leading up to a mid-year summit attended by the heads of government. The president of the European Commission participates as an equal in all summit events.
The ministerial meetings bring together ministers responsible for various portfolios to discuss issues of mutual or global concern. The range of topics include health, law enforcement, labor, economic and social development, energy, environment, foreign affairs, justice and interior, terrorism, and trade. There are also a separate set of meetings known as the G8+5, created during the 2005 Gleneagles, Scotland summit, that is attended by finance and energy ministers from all eight member countries in addition to the five "outreach countries" which are also known as the Group of Five — Brazil, People's Republic of China, India, Mexico, and South Africa.
In June 2005, justice ministers and interior ministers from the G8 countries agreed to launch an international database on pedophiles. The G8 officials also agreed to pool data on terrorism, subject to restrictions by privacy and security laws in individual countries.
See main article: International Partnership for Energy Efficiency Cooperation and Climate Investment Funds.
At the Heiligendamm Summit in 2007, the G8 acknowledged a proposal from the EU for a worldwide initiative on efficient energy use. They agreed to explore, along with the International Energy Agency, the most effective means to promote energy efficiency internationally. A year later, on 8 June 2008, the G8 along with China, India, South Korea and the European Community established the International Partnership for Energy Efficiency Cooperation, at the Energy Ministerial meeting hosted by Japan holding 2008 G8 Presidency, in Aomori.
G8 Finance Ministers, whilst in preparation for the 34th Summit of the G8 Heads of State and Government in Toyako, Hokkaido, met on the 13 and 14 June 2008, in Osaka, Japan. They agreed to the “G8 Action Plan for Climate Change to Enhance the Engagement of Private and Public Financial Institutions.” In closing, Ministers supported the launch of new Climate Investment Funds (CIFs) by the World Bank, which will help existing efforts until a new framework under the UNFCCC is implemented after 2012.
The annual G8 leaders summit is attended by the heads of government The member country holding the G8 presidency is responsible for organizing and hosting the year's summit.
The serial annual summits can be parsed chronologically in arguably distinct ways, including as the sequence of host countries for the summits has recurred over time, series, etc.
|Date||Host country||Host leader||Location held||Website||Notes|
|1st||November 15–17, 1975||Valéry Giscard d'Estaing||Rambouillet (Castle of Rambouillet)||G6 Summit|
|2nd||June 27–28, 1976||Gerald R. Ford||Dorado, Puerto Rico||Also called "Rambouillet II;" Canada joins the group, forming the G7|
|3rd||May 7–8, 1977||James Callaghan||London||President of the European Commission is invited to join the annual G-7 summits|
|4th||July 16–17, 1978||Helmut Schmidt||Bonn, North Rhine-Westphalia|
|5th||June 28–29, 1979||Masayoshi Ōhira||Tokyo|
|6th||June 22–23, 1980||Francesco Cossiga||Venice|
|7th||July 20–21, 1981||Pierre E. Trudeau||Montebello, Quebec|
|8th||June 4–6, 1982||François Mitterrand||Versailles|
|9th||May 28–30, 1983||Ronald Reagan||Williamsburg, Virginia|
|10th||June 7–9, 1984||Margaret Thatcher||London|
|11th||May 2–4, 1985||Helmut Kohl||Bonn, North Rhine-Westphalia|
|12th||May 4–6, 1986||Yasuhiro Nakasone||Tokyo|
|13th||June 8–10, 1987||Amintore Fanfani||Venice|
|14th||June 19–21, 1988||Brian Mulroney||Toronto|
|15th||July 14–16, 1989||François Mitterrand||Paris|
|16th||July 9–11, 1990||George H. W. Bush||Houston, Texas|
|17th||July 15–17, 1991||John Major||London|
|18th||July 6–8, 1992||Helmut Kohl||Munich, Bavaria|
|19th||July 7–9, 1993||Kiichi Miyazawa||Tokyo|
|20th||July 8–10, 1994||Silvio Berlusconi||Naples|
|21st||June 15–17, 1995||Jean Chrétien||Halifax, Nova Scotia|||
|22nd||June 27–29, 1996||Jacques Chirac||Lyon||International organizations' debut to G8 Summits periodically. The invited ones here were: United Nations, World Bank, International Monetary Fund and the World Trade Organization.|
|23rd||June 20–22, 1997||Bill Clinton||Denver, Colorado||||Russia joins the group, forming G8|
|24th||May 15–17, 1998||Tony Blair||Birmingham, England|||
|25th||June 18–20, 1999||Gerhard Schröder||Cologne, North Rhine-Westphalia||||First Summit of the G-20 major economies at Berlin|
|26th||July 21–23, 2000||Yoshiro Mori||Nago, Okinawa||||Formation of the G8+5 starts, when South Africa was invited. Since then, it has been invited to the Summit annually without interruption. Also, with permission from a G8 leader, other nations were invited to the Summit on a periodical basis for the first time. Nigeria, Algeria and Senegal accepted their invitations here. The World Health Organization was also invited for the first time, too.|
|27th||July 20–22, 2001||Silvio Berlusconi||Genoa||||Leaders from Bangladesh, Mali and El Salvador accepted their invitations here. Demonstrator Carlo Giuliani is shot and killed by police during a violent demonstration. One of the largest and most violent anti-globalization movement protests occurred for the 27th G8 summit. Following those events and the September 11 attacks two months later in 2001, the G8 have met at more remote locations.|
|28th||June 26–27, 2002||Jean Chrétien||Kananaskis, Alberta||||Russia gains permission to officially host a G8 Summit.|
|29th||June 2–3, 2003||Jacques Chirac||Évian-les-Bains||http://www.g8.fr/||The G8+5 was unofficially made, when China, India, Brazil, and Mexico were invited to this Summit for the first time. South Africa has joined the G8 Summit since 2000. Other first-time nations that were invited by the French president included: Egypt, Morocco, Saudi Arabia, Malaysia and Switzerland.|
|30th||June 8–10, 2004||George W. Bush||Sea Island, Georgia||||A record number of leaders from 12 different nations accepted their invitations here. Amongst a couple of veteran nations, the others were: Ghana, Afghanistan, Bahrain, Iraq, Jordan, Turkey, Yemen and Uganda. Also, the state funeral of former president Ronald Reagan took place in Washington during the summit.|
|31st||July 6–8, 2005||Tony Blair||Gleneagles, Scotland||||The G8+5 was officially formed. On the second day of the meeting, suicide bombers killed 52 people on the London Underground and a bus. Nations that were invited for the first time were Ethiopia and Tanzania. The African Union and the International Energy Agency made their debut here. During the 31st G8 summit in United Kingdom, 225,000 people took to the streets of Edinburgh as part of the Make Poverty History campaign calling for Trade Justice, Debt Relief and Better Aid. Numerous other demonstrations also took place challenging the legitimacy of the G8.|
|32nd||July 15–17, 2006||Vladimir Putin||Strelna, St. Petersburg||http://en.g8russia.ru/||First G8 Summit on Russian soil. Also, the International Atomic Energy Agency and UNESCO made their debut here.|
|33rd||June 6–8, 2007||Angela Merkel||Heiligendamm, Mecklenburg-Vorpommern||http://www.g-8.org/||Seven different international organizations accepted their invitations to this Summit. The Organisation for Economic Co-operation and Development and the Commonwealth of Independent States made their debut here.|
|34th||July 7–9, 2008||Yasuo Fukuda||Toyako (Lake Toya), Hokkaido||||Nations that accepted their G8 Summit invitations for the first time are: Australia, Indonesia and South Korea.|
|35th||July 8–10, 2009||Silvio Berlusconi||L'Aquila, Abruzzo||http://www.g8italia2009.it||This G8 Summit was originally planned to be in La Maddalena (Sardinia), but was moved to L'Aquila as a way of showing Prime Minister Berlusconi's desire to help the region in and around L'Aquila after the earthquake that hit the area on the April 6th, 2009. Nations that accepted their invitations for the first time were: Angola, Denmark, Netherlands and Spain. A record of TEN (10) international organizations were represented in this G8 Summit. For the first time, the Food and Agriculture Organization, the International Fund for Agricultural Development, the World Food Programme, and the International Labour Organization accepted their invitations.|
|36th||June 25–26, 2010||Stephen Harper||Huntsville, Ontario||||Malawi, Colombia, Haiti, and Jamaica accepted their invitations for the first time.|
|37th||May 26–27, 2011||Nicolas Sarkozy||Deauville,  Basse-Normandie||||Guinea, Niger, Côte d'Ivoire and Tunisia accepted their invitations for the first time. Also, the League of Arab States made its debut to the meeting.|
|38th||May 18–19, 2012||Barack Obama||Camp David||The summit was originally planned for Chicago, along with the NATO summit, but it was announced officially on March 5, 2012, that the G8 summit will be held at the more private location of Camp David and at one day earlier than previously scheduled.|
|39th||2013||David Cameron||TBD||Britain hopes to refocus the event, possibly by discussing a single issue such as the Middle East and inviting key players, such as Turkey or Israel. David Cameron is critical of the value and cost of the G8 if there is too much focus on communiqués as opposed to building trust between world leaders. He has been looking at the idea of attaching the G8 summit to another event such as the UN general assembly.|
All eight of the G8 countries are amongst the thirteen top-ranked leading export countries. Six of the G8 countries are among the top 10 with the largest gold reserves (USA, Germany, Italy, France, Russia and Japan.)Some of the world's 18 largest major stock exchanges by traded value and market capitalization are in G8 countries (U.S., Japan, UK, Canada, Germany, Russia.) G8 countries are represented in the top eleven economies (by nominal GDP) of the world, according to latest (2010 data) International Monetary Fund's statistics. Also, five countries of the G8 have nominal GDP per capita above US$40,000 (USA, Canada, Japan, France, Germany), from the same 2010 IMF data. However, only four of the G8 nations have a sovereign wealth fund, administered by either a national or a state/provincial government (Russia, USA, France, Canada). Along with that, the G8 are ranked in the top thirty of nations with large amounts of foreign-exchange reserves in their central banks. The G8 nations also have some of the world's largest, most technologically advanced, and most powerful militaries. Four of the G8 nations have nuclear weapons in operation (France, Russia, UK, USA),  three others have the capability to rapidly produce nuclear warheads (Canada, Germany, Japan), and some have nuclear weapons sharing programs (Canada, Germany, Italy).  
A few of the world's 10 largest oil producers (Russia, USA, and Canada) and the countries with the third and eighth largest oil reserves (Canada and Russia respectively) are in the G8. Seven of the nine largest nuclear energy producers are in the G8 (USA, France, Japan, Russia, Germany, Canada, UK), even though Germany will wean itself from nuclear power by 2022. The 7 largest donors to the UN budget for the 2011 annual fiscal year are in the G8 (U.S., Japan, Germany, UK, France, Italy, Canada.) The G8 and the BRIC countries makes up almost all of the 15-nation "trillion dollar club of nations." All of the G8 and G8+5 countries (minus South Africa) are in the top twenty nations that are ranked by the amount of voting power and special drawing rights (SDRs) in the IMF organization.
Together the eight countries making up the G8 represent about 14% of the world population, but they represent about 60% of the Gross World Product as measured by gross domestic product, all eight nations being within the top 12 countries according to the CIA World Factbook. (see the CIA World Factbook column in List of countries by GDP (nominal)), the majority of global military power (seven are in the top 8 nations for military expenditure), and almost all of the world's active nuclear weapons. In 2007, the combined G8 military spending was US$850 billion. This is 72% of the world's total military expenditures. (see List of countries and federations by military expenditures) Four of the G8 members, the United Kingdom, United States, France and Russia, together account for 96–99% of the world's nuclear weapons. (see List of states with nuclear weapons)
Some criticism centres on the assertion that members of G8 do not do enough to help global problems e.g. debt, global warming and the AIDS problem – due to strict medicine patent policy and other issues related to globalization.
The G8's relevance is unclear. Critics argue that the G8 has now become unrepresentative of the world's most powerful economies. In particular, China has surpassed every economy except the United States, while Brazil has surpassed Canada, Italy and UK (according to the IMF).