AS Prince William and Kate Middleton announce they're expecting their third child, the royal family's hierarchy is about to change once again.
Already behind the couple's two children - Prince George, aged four, and Princess Charlotte, two - Prince Harry will be bumped further down the line by his unborn niece or nephew, and less likely to ever wear the crown.
Here we look at the current line of succession within the British monarchy, and who will take to the throne if the Queen abdicates, retires or dies.
1) Prince Charles, Prince of Wales
Born in 1948, Prince Charles is the eldest of the Queen and Prince Philip's four children and is set to become the next King.
Aged 68, the Prince of Wales is the longest-serving heir apparent in UK history, having been next in line to take the throne since the Queen's coronation in 1952, when he just three-years-old.
His age also means that should he become King, he will be the oldest person to ever be crowned the British monarch.
Charles was the first heir to ever earn a degree, achieving a 2:2 in History from the University of Cambridge in 1970.
The following year, Charles continued family tradition by entering the Army - serving for five years in Royal Navy.
Prince Charles was introduced to Diana Spencer, 13 years his junior, in the 1970s, and the pair tied the knot in St Paul's Cathedral in 1981.
The marriage was widely dubbed "the wedding of the century", with two million spectators lining the streets of London for the big day, and a further 750 million worldwide watching the ceremony live on TV.
The couple welcomed their first son, Prince William, in 1982, and his younger brother Prince Harry was born two years later.
But the "fairy tale marriage" was not to be, and the couple grew apart over the next decade, seemingly strained by a royal responsibilities, personal conflicts, and infidelities.
In 1992 they officially separated, divorcing in 1996 - a year before Princess Diana tragically died in a car crash in Paris.
Prince Charles quietly reignited a romance with a former flame, Camilla Parker Bowles, and the couple announced their engagement in 2005.
The pair wed in a civil ceremony at Windsor Castle, which the Queen and Prince Philip did not attend.
The heir apparent presides over seventeen charitable organisations, collectively called The Princes Charities, the first of which he founded in 1976.
2) Prince William, Duke of Cambridge
Next in line after Charles is Prince William, who was born on 21 June 1982, at St Mary's Hospital in London.
However, many royalists think the crown should pass straight to Wills after the Queen, missing out Charles all together.
After a gap year in which he spent time in Belize and Chile, Prince William returned to the UK in 2001 to attend the University of St Andrews.
His enrolment caused a temporary increase in the number of applications to the Scottish university, mostly from young women hoping to meet the Royal.
But ultimately it was Kate Middleton, a fellow student living in the Prince's halls of residence, who won his heart.
The couple dated for four years before calling it quits in 2007, but the separation was short-lived, and in 2010 it was announced that they were engaged.
The pair tied the knot in a lavish ceremony at Westminster Abbey on 29 April 2011, and two years later welcomed their first son, Prince George.
The young family left London in favour of Norfolk, and two years later, Princess Charlotte was born.
Prince William followed in his father's footsteps by joining the armed forced - serving in the Army, and briefly the Navy, from 2005, before transferring to the RAF in 2009.
William retired from his position as a search and rescue pilot in 2013, and a year took up a full-time role as a pilot with the East Anglian Air Ambulance.
In July 2017 it was announced that William would retire from this role to focus on his royal duties.
3) Prince George of Cambridge
Adorable Prince George may only be four-years-old, having been born on 22 July 2013, but he is third in line to the throne, after his dad and grandfather.
Ahead of the tot's birth, the Royal Family underwent a major change - rewriting historic laws which traditionally gave male heirs preference to the throne - so that the newborn would one day be able to reign whatever their sex.
At less than a year old, George embarked on his first royal tour in April 2014, travelling Australia and New Zealand with his parents.
The public couldn't get enough of the pictures of the cute young royal, and as the three week trip came to an end, the BBC said "there's no doubt Prince George stole the limelight".
In March 2017, it was announced that George would start school in September, attending Thomas' School in Battersea, where fees start at £17,604 a year.
4) Princess Charlotte of Cambridge
Prince George's younger sister Princess Charlotte was welcomed into the world on 2 May 2015.
Ten hours after her birth, the public got their first glimpse of Charlotte, as her parents posed for pictures outside the London hospital.
Two days later the tot's name was announced as Charlotte Elizabeth Diana - her middle names paying tribute to both the Queen and Prince William's late mother - and landmarks across the capital were subsequently illuminated pink.
For her first birthday, Charlotte received gifts from 64 countries, including a £30,000 white gold toy rattle from The Natural Sapphire Company in the US.
On 20 May 2017, two-year-old Charlotte joined her elder brother George to accompany their aunt Pippa Middleton down the aisle as bridesmaid and page boy.
5) Prince Harry of Wales
Up until 2013, Prince William's 32-year-old brother Prince Harry had been third in line to become King. Initially pushed back one place in the royal rankings by the birth of his nephew Prince George, two years on he ended up in fifth place behind Princess Charlotte.
Born in London on 15 September 1984 to Prince Charles and Princess Diana, Harry grew up under the scrutiny of the public eye.
His wild antics in his late teens and early twenties earned him the nickname "the party Prince" in the tabloids, although the Prince left the prestigious Eton College with two A-levels in 2003, making him eligible to apply for an officer commission in the British Army.
After a gap year spent working first on a cattle station in Australia and later with orphans in Lesotho, Harry entered a decade of service in the Army in 2005, during which time he completed two tours of Afghanistan.
Harry has had a string of romances, reportedly spending seven years in an on-off relationship with Chelsy Davy; with whom he finally split for good in 2011.
The following year, Prince Harry's cousin Princess Eugenie introduced him to Cressida Bonas, and the couple dated until 2014.
Most recently, it was announced in November 2016 that Harry is dating American actress Meghan Markle, and close friends have speculated that the loved-up couple are likely to tie the knot.
In 2014, Prince Harry launched the Invictus Games, an international Paralympic-style event for wounded, injured or sick troops and veterans.
6) Prince Andrew, Duke of York
As of 2017, the second son and third child of the Queen and Prince Philip is sixth in line to the throne. Prince Andrew was born on 19 February 1960.
Unlike his older brother Prince Charles, Andrew opted not to go to university, instead entering the Royal Navy in 1979.
In 1982, the Prince served in the Falklands War when the Queen overruled the Cabinet's warnings against him doing so.
The Prince continued his naval career up until 2001, and these days holds the title of Honorary Vice Admiral.
Andrew married Sarah Ferguson on 23 July 1986, and the couple went on to have two daughters, Princess Beatrice and Princess Eugenie. In March 1992, it was announced that Andrew and Sarah had split, although they did so amicably, sharing custody of their children.
7) Princess Beatrice of York
The eldest of Prince Andrew and Sarah Ferguson's daughters, Princess Beatrice, was born on 8 August 1988.
Beatrice spent three-years studying for a BA in History and History of Ideas at Goldsmiths College, London, graduating in 2011 with a 2:1.
The royal spent ten years in a relationship with businessman Dave Clark, but the couple called it quits in July 2016 - reportedly over his refusal to get married.
In an embarrassing blow to Beatrice, Dave announced his engagement to New York advertising executive Lynn Anderson, 31, just months after their split.
In 2016 Beatrice made headlines when she apparently sliced Ed Sheeran's face open with a ceremonial sword while pretending to 'knight' singer James Blunt, although James later denied these claims.
8) Princess Eugenie of York
Two years after Beatrice's birth, her younger sister Princess Eugenie was born on 23 March 1990.
In 2009, Eugenie began studying for a degree in English literature and history of art at Newcastle University, graduating three years later with a 2:1.
After a stint living in New York, the Princess returned to London and got a job at an art gallery in 2015, although she later came under fire with allegations she'd taken five weeks off within her first ten weeks of work.
In late 2016, it was rumoured Eugenie had secretly got engaged to boyfriend of six years Jack Brooksbank, when she was spotted with a simple band on her ring finger.
9) Prince Edward, Earl of Wessex
The youngest of the Queen's children, Prince Edward, was born on 10 March 1964 and is now ninth in line to the throne.
After studying at Cambridge University, Edward enrolled in the Royal Marines, but dropped out after just a third of his 12 month training period.
The Prince then moved into a career in entertainment, first working for Andrew Lloyd Webber's theatre company, before setting up his own TV production company in 1993.
The venture was not a success, with the firm reporting losses every year except for one where Edward did not take a salary - and eventually it voluntarily dissolved in June 2009.
Prince Edward married Sophie Rhys-Jones in 1999, and the couple later went on to have two children.
10) James, Viscount Severn
The Queen's youngest grandchild, nine-year-old James, Viscount Severn, is tenth in line to the throne.
Born on 17 December 2007, before the law changed with the Succession to the Crown Act 2013, James is higher in the royal rankings than his elder sister Louise.
11) Lady Louise Windsor
Eleventh in line to the throne is Edward's 13-year-old daughter Louise, who was born prematurely on 8 November 2003 and spent two weeks in hospital after her birth.
Louise was born with an eye condition called estropia, and has had two operations to correct her vision - the second of which, in 2013, was successful.
In 2011, Louise was one of Kate Middleton's bridesmaids at her wedding to Prince William.
12) Princess Anne
The Queen's only daughter, Princess Anne, was third in line to the throne when she was born on 15 August 1950, but as of 2017 is twelfth in line.
Anne is famed for her equestrian talents, and was voted BBC Sports Personality of the Year aged 21 when she won the individual title at the European Eventing Championship.
She competed with the British team for the next five years, becoming the first Royal to compete in an Olympic Games in 1976 - where she rode the Queen's horse.
The Princess married Mark Phillips in a televised ceremony in 1973, and the couple went on to have two children, Peter and Zara, before announcing their separation in 1989.
Within months of the divorce being finalised in 1992, Anne walked down the aisle for a second time, this time marrying Timothy Laurence.
In August 2017 it was announced Princess Anne is the hardest working royal.
13) Peter Phillips
The Queen's first grandchild, Peter Phillips, was born on 15 November 1977 and is currently thirteenth in line of succession to the throne.
Peter's parents, Princess Anne and Mark Phillips, reportedly declined the Queen's offers of peerage, and as such he became the first grandchild of a monarch to be born without an official title for over 500 years.
Since graduating from Exeter University, Peter has worked for Jaguar and the WilliamsF1 racing team, before going into banking, and then sports sponsorship.
Peter has two children with Autumn Kelly, a Canadian management consultant whom he married in May 2008.
14) Savannah and 15) Isla Phillips
In 2011, Peter Phillip's wife Autumn gave birth to the Queen's first great-grandchild, Savannah Phillips, who is fourteenth in line to the throne.
The following year, the couple's second daughter Isla, now aged five, was born and became fifteenth in line.
Like their father, neither child has an official royal title.
16) Zara Phillips
Four years after Peter's birth, Princess Anne gave birth to her second child, Zara Phillips, on 15 May 1981.
Following in her mother's footsteps, Zara is an equestrian who won the Eventing World Championship in 2006 and was subsequently voted BBC Sports Personality of the Year.
The following year she received an MBE for her services to Equestrianism. In 2012, Zara went on to win a silver medal at the London Olympics.
In July 2011, Zara married former England rugby union captain Mark Tindall, opting to take his last name and become Zara Tindall.
On 17 January 2014, Zara gave birth to the couple's daughter, Mia, who is seventeenth in line to the throne.
On Christmas Eve 2016, Zara and Mike were left heartbroken when she miscarried their second child.