The throne was passed to Charles immediately after the Queen's death.
There are a number of steps he must take to be crowned King.
His name will be King Charles III.
The new king made that decision. He could have picked any of his four names.
There are other people who face a change of title as well.
Prince William won't become Prince of Wales immediately. He immediately became the Duke of Cornwall. He will be known as the Duke of Cornwall.
A new title will be given to Charles' wife, who will be known as Queen Consort.
After his mother's death, Charles will be declared King. The Accession Council is located at St James's Palace in London.
This is made up of members of the Privy Council, as well as some senior civil servants and the Lord Mayor of London.
In theory, more than 700 people are entitled to attend, but given the short notice, the actual number is likely to be much lower. About 200 people attended the last accession council.
The king doesn't usually attend.
The Lord President of the Privy Council will announceQueen Elizabeth's death at the meeting.
The previous monarch has traditionally been praised and pledged support for the new one in a series of prayers and pledges.
A number of senior figures, including the prime minister, the archbishop and the lord chancellor, sign the proclamation.
There will be attention paid to what may have been changed, added or updated as a sign of a new era.
The King will join the Privy Council at the Accession Council's next meeting.
The style of "swearing in" at the beginning of a British monarch's reign is different to that of the President of the US. The tradition of making an oath to preserve the Church of Scotland dates back to the early 18th century.
Charles will be declared the new King after a ceremony. The Garter King of Arms will make this from a balcony above the court.
When the national anthem is played, he will say "God save the King" and for the first time in 60 years, the words will be "God Save the King".
There will be gun salutes in Hyde Park, the Tower of London, and naval ships, as well as the announcement of Charles as the King.
The crowning of Charles will be the high point of the accession. In February 1952, Queen Elizabeth succeeded to the throne, but was not crowned until June 1953.
William the Conqueror was the first monarch to be crowned in the abbey and Charles will be the 40th.
The service is conducted by the archbishop. The St Edward's Crown will be placed on Charles's head at the end of the ceremony.
The centerpiece of the Crown Jewels at the Tower of London is only worn by the monarch at the time of their crowning.
The guest list is decided by the government, unlike a royal wedding.
The new monarch will be anointed using oils of orange, roses, cinnamon, Musk and ambergris.
In front of the world, the new King will take the oath of office. The orb and sceptre he will receive as symbols of his new role will be placed on his head by the archbishop.
The Commonwealth is an association of 56 independent countries and over 2 billion people. The King is the head of state in 14 of them.
The Commonwealth is made up of Australia, Antigua and Barbuda, the Bahamas, Canada, Grenada, Jamaica, New Zealand, Solomon Islands, St Kitts and Nevis, and St Lucia.
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