A voluntary association of 56 independent and equal countries.
Some of these countries were previously in the British Empire, some are still British dominions, while others had no colonial links to Britain but have chosen to join the global club.
About 2.5 billion people - out of a global population of eight billion - live in the 56 Commonwealth countries.
King Charles is the head of state in 14 Commonwealth countries - or realms - in addition to the UK.
Most countries in the club are republics - with Barbados the last to remove the UK monarch as its head of state in 2021.
Former French colonies Gabon and Togo are the most recent joiners, becoming members in June 2022.
South Africa withdrew in 1961 after it was criticised by Commonwealth members for its apartheid policies. It became a member again in 1994.
The UK is no longer the biggest economy in the Commonwealth, according to the latest GDP numbers from the International Monetary Fund, with India overtaking it for the first time in 2022.
The modern Commonwealth was formed in 1949, after “British” was dropped from the name and allegiance to the Crown was removed.
The Commonwealth has been criticised for being a post-colonial club and for having little influence in the modern world.
Russia and a number of other former members of the Soviet Union set up the Commonwealth of Independent States in 1991.
More than half a billion dollars that could have been spent on new schools, hospital wings or upgrades to suburban roads has instead been squandered on a Commonwealth Games that will not be held in Victoria.
What type of law is effective in the Commonwealth ? The Common Law
What did the 1926 Balfour Declaration establish? Dominions are equal in status and not subordinate to the UK
Dominions are united by common allegiance to the Crown
What is the Commonwealth Charter and when was it signed ? Adopted in Perth in 2012, signed by the Queen in 2013.