WHAT HAS HAPPENED ?
Queen Elizabeth II, the UK's longest-serving monarch, has died at Balmoral aged 96, after reigning for 70 years.
The Queen came to the throne in 1952 and witnessed enormous social change.
Prime Minister Liz Truss, who was appointed by the Queen on Tuesday, said the monarch was the rock on which modern Britain was built, who had "provided us with the stability and strength that we needed".
Queen Elizabeth II's tenure as head of state spanned post-war austerity, the transition from empire to Commonwealth, the end of the Cold War and the UK's entry into - and withdrawal from-the European Union.
Her reign spanned 15 prime ministers starting with Winston Churchill, born in 1874, and including Ms Truss, born 101 years later in 1975.
HOW IS THE BRITISH CROWN INHERITED?
Britain has a hereditary monarchy. This means that the role of king or queen is passed down in the family. There are special rules to decide who can inherit the crown.
The monarch's first child is first in line to the throne. This child is the Prince or Princess of Wales, currently Prince Charles. He becomes the monarch when Queen Elizabeth II dies.
Charles' first child (with Diana, Princess of Wales) was Prince William, who is second in line to the throne.
Prince William's son George is third in line. Until Prince George grows up and has children of his own, Princess Charlotte is fourth in line.
There are hundreds of further royals in line to the throne just in case, including Prince William's younger brother Prince Harry, who is now fifth, but they are very unlikely to inherit.
HOW ELIZABETH BECAME THE QUEEN?
The Queen was born Elizabeth Alexandra Mary Windsor, in Mayfair, London, on 21 April 1926. Few could have foreseen she would become monarch but in December 1936 her uncle, Edward VIII, abdicated from the throne to marry the twice-divorced American, Wallis Simpson.
Elizabeth's father became King George VI and, at age 10, Lilibet, as she was known in the family, became heir to the throne. Within three years, Britain was at war with Nazi Germany. Elizabeth and her younger sister, Princess Margaret, spent much of wartime at Windsor Castle after their parents rejected suggestions they be evacuated to Canada. Elizabeth married to Philip, Prince of Greece on 20 November 1947, with the prince taking the title of Duke of Edinburgh.
Princess Elizabeth was in Kenya in 1952, representing the ailing King, when Philip broke the news that her father had died. She immediately returned to London as the new Queen.
Elizabeth was crowned on 2 June 1953, aged 27, in front of a then record TV audience estimated at more than 20 million people.
Their first son, Charles, was born in 1948, followed by Princess Anne, in 1950, Prince Andrew, in 1960, and Prince Edward, in 1964.
It's a sad time, but one that the Crown has been preparing for since the 1960s.
The plan for what to do after Elizabeth's death is called Operation London Bridge, and the steps that will be taken now that the Queen has died are strictly controlled.
THE CALL
It starts with a phone call. At the time of the Queen's death, Sir Edward Young, her private secretary, called the Prime Minister and said "London Bridge is down."
It was just Tuesday that Elizabeth met with and appointed newly installed U.K. Prime Minister Liz Truss following the resignation of Boris Johnson, who bid his farewell to the Queen earlier that day.
THE NOTIFICATION
After the Prime Minister had been alerted, news went out to the 15 governments where the Queen was still head of state, including Jamaica, New Zealand, Australia, Papua New Guinea, Canada, and the Bahamas.
After that, officials in the 38 other nations in the Commonwealth were alerted to the news.
A footman dressed in black pinned an official notice to the gates of Buckingham Palace.
THE ALARM AT BBC
At the BBC, there's an alarm that signals national emergencies.
Many who work there had no idea what it sounds like, but it went off when the Queen died.
At that point, the BBC's logo, which is usually red, was changed to black. And all anchors changed into black suits and ties.
TRANSITION OF POWER
Flags were lowered to half-mast and Prince Charles unofficially became king immediately upon Elizabeth's death.
He is expected to make his first speech as head of state as early as this evening, though that has not been formally announced.
On Friday, flags will be raised again and at 11:00 a.m. local time, Charles will officially become king and Camilla will become the U.K.'s queen.
THE FUNERAL
Four days after Elizabeth's death, there will be a procession from Buckingham Palace to Westminster Hall. Elizabeth will lie in state for four days, and she will be be buried nine days after her passing.
Two thousand invited guests, largely heads of state, will attend in person. The funeral will be broadcast globally.
Elizabeth is expected to then be buried next to her late husband, Prince Philip, and her father, King George VI.
Some of the exemptions Queen had:
• The Queen and her royal family were exempted from anti-discrimination laws. • The Queen was exempted from being charged under any civil or criminal suit, for being the head of the state.
• It was not mandatory for the Queen to carry a driver's license.
• The British passport is issued in the name of Her Majesty, so she never had to own one.
• The British monarchy is exempted from giving any explanation under the Freedom of Information Act.
Countries where she was formerly Head of State
1. Barbados
2. Sri Lanka
3. Fiji
4. The Gambia
5. Ghana
6. Guayana
7. Kenya
8. Malawi
9. Malta
10. Mauritius
11. Nigeria
12. Pakistan
13. Sierra Leone
14. South Africa
15. Tanzania
16. Trinidad and Tobago
17. Uganda
Countries the UK Queen was Head of State at the time her passing
1. United Kingdom
2. Antigua and Barbuda
3. Australia
4. The Bahamas
5. Belize
6. Canda
7. Grenada
8. Jamaica
9. New Zeland
10. Papua New Guinea
11. St Kitts and Nevis
12. Saint Lucia
13. St Vincent and the Grenadines
14. Solomon Islands
15. Tuvalu
