Elizabeth II is the Queen of 16 sovereign states and territories known as the Commonwealth realms. She has reigned since 1952, making her reign the second longest of any British monarch at over 60 years so far. Elizabeth was born in 1926 in London and became heir presumptive when her uncle abdicated the throne in 1936 and her father became King George VI. She began undertaking public duties during World War 2 and married Prince Philip in 1947, with whom she has four children.