- Elizabeth has reigned for 65 years and 75 days.
Friday marks Queen Elizabeth II's 91st birthday.
She is the world's oldest reigning monarch as well as Britain's longest-lived.
The Queen Elizabeth was born on April 21, 1926 in Bruton Street in central London when Calvin Coolidge was U.S. president and Joseph Stalin had just taken control of the Soviet Union.
In London, a troop of the Royal Horse Artillery rode horse-and-gun carriages past Buckingham Palace before firing a 41-gun salute in Hyde Park at noon.
But royal gun salutes will still echo across the capital later, fired by the King's Troop Royal Horse Artillery and the Honourable Artillery Company.
Last June, London was a buzz for Her Majesty's 90 birthday celebrations and no doubt we can expect more pomp and ceremony again later this year.
To mark her 18th birthday, Elizabeth is given a Welsh corgi, Susan, the first of around 30 she will go on to have.
25 - age when she became Queen on February 6 1952.
While her eldest child Prince Charles is heir to the throne, greater attention has fallen on his two sons William and Harry, who have taken on some of the Queen's duties.
The Queen also celebrates an "official birthday" which falls on the second Saturday in June. The Queen is also exempt from having license plates on her state cars. She's the longest-serving British monarch ever, breaking the record set by Queen Victoria, her great-great grandmother, in 2015.
Though Queen Elizabeth II's birthday stands a much better chance at seeing sunny weather, the tradition continues.
Lee Cohen, New York Director of The Anglosphere Society, spent years advising the U.S. House of Representatives Foreign Affairs Committee on Western European affairs, and was founding Executive Director of the House United Kingdom Caucus.
601 - charities, organisations and military regiments of which the Queen is patron.
When she was four, the Queen's grandfather King George V gave her her first horse, a Shetland pony called Peggy.
£340 million - the Queen's wealth, according to The Sunday Times' Rich List.