The Commonwealth currently has 53 associated countries which between them represent all six of our continents.
Together they boast more than two billion citizens - almost a third of the world population, and representing all faiths and ethnicities.
India's 1.2 billion people make it by far the largest Commonwealth country while the smallest is Tuvalu, a group of nine small islands in the western Pacific, totallling around 10,000 people.
Most recent members are: Rwanda, Cameroon and Mozambique, the latter being the first to join with no historical or previous administrative association to the Commonwealth.
Together, the landmass of all Commonwealth members totals around 12,200,000 square miles - about 21% of the total world land area.
At last count, Commonwealth countries constituted more than 40% of the World Trade Organisation, handling annual trade worth an estimated $1.7trillion, bigger than the EU.