With her Platinum Jubilee this year, the Queen marked a milestone no other British royal had ever reached - 70 years on the throne.
But which royals are set to take on the immense challenge of filling her shoes when her reign ends?
We take a look at who's who in the line of succession.
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First in line: Prince Charles
The first heir to the throne is known for being passionate about the environment
Charles is the firstborn son of the Queen and the late Duke of Edinburgh. He was born on 14 November 1948 in Buckingham Palace, London, and went on to be educated in Britain and Australia, before studying archaeology, anthropology, and history at Trinity College, Cambridge.
READ: All the times Prince Charles has spoken about his love for the environment
The heir apparent is known for being quite outspoken, despite the fact that members of the royal family don't usually voice their political opinions publicly. He is passionate about environmental issues, having worked to make the Queen's estate more sustainable as well as making eco-friendly changes to his own.
Charles has two sons, Prince William and Prince Harry, from his first marriage to the late Diana, Princess of Wales, and he is currently married to the Duchess of Cornwall.
Second in line: Prince William
The Duke is set to move his family closer to the Queen's Windsor estate
Prince William is the eldest son of Prince Charles and was born on 21 June 1982 in St Mary's Hospital, London, breaking tradition as the first direct heir to the throne to be born outside palace walls.
The Duke also shares his father's concern about climate change, having launched the Earthshot Prize in 2020 to award those who come up with innovative ways of tackling the world's biggest environmental challenges.
READ: 12 photos that show the Queen's close bond with her grandson Prince William
He has three children - Prince George, Princess Charlotte, and Prince Louis - who he shares with his wife Kate, whom he met whilst studying at the University of St. Andrews.
Third in line - Prince George
Prince George watched the Wimbledon final from the Royal Box in 2022
Named after the Queen's father and grandfather, Prince George was born in London on 22 July 2013 to fanfare and celebration: the bells at Westminster Abbey rang out for three hours, and there were gun salutes in Green Park and the Tower of London to welcome him.
READ: The reason why Kate Middleton and Prince William took George to Wimbledon and not Charlotte or Louis
The young Prince takes after his parents' love for tennis, having recently attended Wimbledon for the first time, and he's accompanied his parents to other big sports events in the past, such as the Euro 2020 final.
Fourth in line - Princess Charlotte
The Princess is said to share the Queen's love of horses
Princess Charlotte, the Queen's great-granddaughter, was born on 2 May 2015 in the same hospital as her father and brother.
READ: Why today is so emotional for Prince George and Princess Charlotte
Even though she's his younger sister, Charlotte has been known to keep her brother George on his toes and she also shares his love for football, as her father William revealed in a recent visit to the England Women's team.
Fifth in line - Prince Louis
Prince Louis delighted the nation with his antics during the Platinum Jubilee celebrations
The youngest Cambridge sibling, Prince Louis, was born on 27 April 2018 at St Mary's, the same hospital where his father and older siblings came into the world.
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The four-year-old Prince is known for being playful and mischievous, just like most other kids his age, and is the only one of his siblings who has lived in London for the majority of his life, although the family is likely to relocate soon.
Sixth in line - Prince Harry
The red-haired Duke is known for his sense of humour
Prince Harry is the youngest son of Prince Charles and the late Princess Diana, and was born on 15 September 1984.
PHOTOS: 12 times Prince Harry made us laugh
After meeting Suits actress Meghan Markle in 2016, the couple got married at St. George's Chapel in Windsor two years later. Their first child, Archie Mountbatten-Windsor, was born in 2019 and their daughter, Lilibet Mountbatten-Windsor, followed in 2021.
READ: Meghan Markle and Prince Harry's unusual upcoming date revealed
In a move that shocked the world, Harry and Meghan stepped back from royal duties in March 2020 and now reside in Montecito in the US.
Seventh in line - Archie Mountbatten-Windsor
Harry and Meghan's first son is their only child born in the UK
READ: Why Prince William and Prince Harry's children have different surnames
The eldest son of Harry and Meghan, Archie was born on 6 May 2019 at the Portland Hospital in London and was introduced to the world at a photocall in Windsor Castle a few days later.
The three-year-old hasn't only inherited his father's red hair - he also takes after Harry's mischievous personality and shares his star sign with his great-grandmother, the Queen!
Eighth in line - Lilibet Mountbatten-Windsor
Harry and Meghan's youngest child is named in honour of her great-grandmother
Lilibet is the youngest in the Sussex family. She became the first royal of such high rank to be born Stateside on 4 June 2021, when her mother gave birth to her at Santa Barbara Cottage Hospital in California.
MORE: Friend of the royals reveals the Queen had no idea Prince Harry and Meghan Markle would name daughter Lilibet
Lilibet's name comes from the Queen's childhood nickname, and her middle name is Diana, to honour her late grandmother.
Ninth in line - Prince Andrew
The Queen's second son has been the source of much controversy
The Duke of York - the second son and the third child of the Queen and the Duke of Edinburgh - was born on 19 February 1960 at Buckingham Palace, the same place his older brother Charles was born.
A Falklands War veteran with a 20-year career in the Royal Navy, Andrew married Sarah Ferguson in 1986 and they went on to have two children together: Princess Beatrice and Princess Eugenie.
MORE: Prince Andrew returns to royal circuit after 'family decision' is made
The couple separated in 1996 and the Duke stepped back from royal duties in 2019 after a BBC Newsnight interview, which focused on his connections to convicted sex offender Jeffrey Epstein.
Tenth in line - Princess Beatrice
The Princess is not a working member of the royal family
Born on 8 August 1988 at Portland Hospital in London to Prince Andrew and Sarah Ferguson, Princess Beatrice was initially fifth in line to the throne, but now ranks tenth.
READ: Princess Beatrice's teeth: a top dentist reveals transformation
Although she is not a working member of the royal family, she has a full-time job as Vice President of Partnerships and Strategy at tech firm Afiniti and is known for her eclectic taste in hats.
She married property developer Edoardo Mapelli Mozzi in July 2020, after their original wedding was postponed due to the pandemic, and gave birth to a daughter, Sienna Elizabeth Mapelli Mozzi, last year.
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