The Commonwealth dates back to the mid-20th century with the decolonisation of the British Empire through increased self-governance of its territories. It was formally constituted by the London Declaration in 1949, which established the member states as "free and equal". The symbol of this free association is Queen Elizabeth II who is the Head of the Commonwealth, but this role does not carry any power with it. While there are over 31 republics and five monarchies who have a different monarch, the Queen is the ceremonial head of state and reigning constitutional monarch of only 16 members of the Commonwealth, known as Commonwealth realms. The position of the crown remains legally distinct from the position of monarch and the position of the Head of the Commonwealth.
Member states have no legal obligation to one another. Instead, they are united by language, history, culture and their shared values of democracy, free speech, human rights, and the rule of law. These values are enshrined in the Commonwealth Charter and promoted by the quadrennial Commonwealth Games.
The Commonwealth covers more than 29,958,050 km2 (11,566,870 sq mi), equivalent to 20% of the world's land area. It spans all six inhabited continents. With an estimated population of 2.419 billion people, nearly a third of the world population, the Commonwealth in 2014 produced a nominal gross domestic product (GDP) of $10.45 trillion, representing 14% of the gross world product when measured nominally and 17% of the gross world product when measured in purchasing power parity (PPP).
Queen Elizabeth II, in her address to Canada on Dominion Day in 1959, pointed out that the confederation of Canada on 1 July 1867 had been the birth of the "first independent country within the British Empire". She declared: "So, it also marks the beginning of that free association of independent states which is now known as the Commonwealth of Nations." As long ago as 1884 Lord Rosebery had described, while visiting Australia, the changing British Empire, as some of its colonies became more independent, as a "Commonwealth of Nations". Conferences of British and colonial prime ministers occurred periodically from the first one in 1887, leading to the creation of the Imperial Conferences in 1911.