The motto is ‘The queen is dead, long live the king’ but the ascension also sets off a stream of changes as etiquette, tradition and circumstance move royals into new roles.
As plans for Queen Elizabeth II’s funeral are firmed up, royals inherit new titles and there are repercussions for members of the ruling family, including Prince Harry and his wife Meghan, the Duke and Duchess of Sussex, who opted out of front-line royal life and moved to California where they live with their two children.
The Duke and Duchess of Sussex plunged the royal family into one of its most challenging periods in modern royal history.
Throughout it, the couple made efforts to publicly praise the queen, even naming their daughter Lilibet after the queen’s family nickname since childhood.
But while Harry and Meghan appear to have invested their time developing their bond with the queen, their relationship with Charles and William has been greatly troubled.
Here's a look at what is happening, after the death of the queen:
The queen's son and successor has become King Charles III of the United Kingdom of Great Britain and Northern Ireland. He is also king of other Commonwealth realms.
He is defender of the faith and supreme governor of the Church of England.
In 2015 he said he would be sworn in as defender of the (Anglican) faith when he became king. "It always seems to me that while at the same time being Defender of the Faith, you can also be protector of faiths," the royal said.
King Charles is also now the Duke of Lancaster
She is now queen consort, like the queen mother was, rather than a queen regent, who rules in her own right, such as Elizabeth II.
Queen Elizabeth II publicly endorsed her daughter-in-law to be known as queen consort in her platinum jubilee message to the nation in February.
William is first in line to become king
He is still the Duke of Cambridge but also becomes the Duke of Cornwall, taking over the title from King Charles III.
Prince William is not yet the Prince of Wales, a title traditionally, but not automatically, given to the male heir to the throne.
In Scotland, he inherits the Scottish titles the Duke of Rothesay, Earl of Carrick, Baron of Renfrew, Lord of the Isles and Prince and Great Steward of Scotland.
His wife, Kate, becomes the Duchess of Cornwall, in addition to being the Duchess of Cambridge. She is also now the Duchess of Rothesay in Scotland, which was also previously Camilla's title. She will presumably become the Princess of Wales, the official title of her late mother-in-law Princess Diana, after her husband's investiture.
George, Charlotte & Louis - second, third and fourth in line
Prince William and his wife Kate's children have become Prince George of Cornwall and Cambridge, Princess Charlotte of Cornwall and Cambridge, and Prince Louis of Cornwall and Cambridge.
They will eventually become "of Wales" when William is the Prince of Wales.
Harry - fifth in line
The Duke and Duchess of Sussex's titles will not change. The couple have stopped using their "Royal Highness" styles, but they still retain them.
Archie - sixth in line
The Duke and Duchess of Sussex's son Archie Mountbatten-Windsor is now technically a prince due to rules set out by King George V in 1917.
When Archie was born he was too far down the line of succession for such a title, according to George V's restrictions, but now, as the son of a son of a sovereign, he can be "His Royal Highness" and a prince.
During Harry and Meghan's interview on Oprah shortly after leaving the UK, one of their complaints was that the family did not want Archie to be a prince and had refused to give him a title.
Lilibet - seventh in line
Archie's younger sister Lilibet Mountbatten-Windsor is now technically a princess.
If she uses the title, she will be Her Royal Highness Princess Lilibet of Sussex.
Like Archie, Charles would have to issue a Letters Patent to remove this.