Prince William through the years
The Duke of Cambridge is the eldest son of Charles, Prince of Wales, and the late Diana, Princess of Wales and has been in the public eye ever since he was born.
Britain's Prince William, The Duke of Cambridge, poses by an air ambulance as he begins his new job with the East Anglian Air Ambulance (EAAA) at Cambridge Airport on July 13, 2015.
The former RAF search and rescue helicopter pilot will work as a co-pilot transporting patients to hospital from emergencies ranging from road accidents to heart attacks.
Prince William and Prince George
Prince William, Duke of Cambridge, and Prince George of Cambridge walk past crowds as they leave the Church of St. Mary Magdalene on the Sandringham Estate after the christening of Princess Charlotte of Cambridge in King's Lynn, England, July 5, 2015.
Prince George
Catherine, Duchess of Cambridge holds Prince George as he and Prince William, Duke of Cambridge look at the Sensational Butterflies exhibition at the Natural History Museum in London, July 2, 2014.
Birth of Princess Charlotte
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge depart the Lindo Wing with their newborn daughter at St Mary's Hospital in London, May 2, 2015. The Duchess delivered a daughter at 8:34am, weighing 8 lbs 3 oz,who will be fourth in line to the throne.
Prince William in Australia
Prince William, Duke of Cambridge holds Prince George of Cambridge as Catherine, Duchess of Cambridge gives him a toy bilby during a visit to the Bilby Enclosure at Taronga Zoo in Sydney, April 20, 2014.
The Duke and Duchess of Cambridge are on a three-week tour of Australia and New Zealand, the first official trip overseas with their son, Prince George of Cambridge.
Prince William
Prince William poses for pictures with his wife, Kate, Duchess of Cambridge, as they leave the King Edward VII hospital in London on Dec. 6, 2012.
Prince William
Prince William, Kate, Duchess of Cambridge and Prince Harry leave after they attended "A Night of Heroes", the annual Sun Military Awards, to honor members of the British armed forces in London on Dec. 19, 2011.
Prince William
Prince William, Duke of Cambridge mingles with David Beckham during a private reception at the British Consul-General's residence in Los Angeles, July 8, 2011.
2012 Olympics
Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge, celebrate during Day 6 of the London 2012 Olympic Games at the Velodrome in London, August 2, 2012.
Prince William
Prince William hugs his wife Kate, Duchess of Cambridge, after competing against her team in a dragon boat race at Dalvay-by-the-Sea on Prince Edward Island as part of their royal tour of Canada, July 4, 2011.
Prince William gets married
As bridesmaid Grace van Cutsem, left, covers her ears, Britain's Prince William kisses his wife Kate, Duchess of Cambridge, on the balcony of Buckingham Palace after the Royal Wedding in London, April, 29, 2011.
Prince William and Kate Middleton engaged
Britain's Prince William and his fiancee Kate Middleton pose for the media at St. James's Palace in London, after they announced their engagement, November 16, 2010. The couple plan to marry in 2011.
Prince William
Prince William, Duke of Cambridge arrives at the Calgary Stampede parade in Calgary, Alberta, Canada, July 8, 2011.
Royal Navy
Prince William is seen aboard a boat during a training session at Britannia Royal Naval college, in Dartmouth, south west England, June 3, 2008.
The prince began a two-month attachment with the Royal Navy. He is an officer in the army but is also training with other parts of the British military, of which he will be commander-in-chief when he becomes king.
Prince William
Prince William, the Duke of Cambridge and a Royal Air Force helicopter pilot, sits at the controls of a Sea King helicopter on March 31, 2011.
Prince William, RAF
TRH Prince William and Prince Harry pose in front of a Griffin helicopter during a photo call at RAF Shawbury in Shawbury, England, June 18, 2009.
Both the Princes are currently on their military helicopter training courses at RAF Shawbury. The base is home of the Defense Helicopter Flying School. Prince William's course will remain at Shawbury until 2010 while Prince Harry will remain at the base until Autumn 2009.
Patron of Centrepoint and Mountain Rescue
Prince William, the Centrepoint and Mountain Rescue patron walks with a group of homeless young people helped by Centrepoint on a fell walk in Cumbria, England, July 24, 2009. They also raised a London 2012 flag to mark three years until the start of the Olympics.
Bearded Prince William
HRH Prince William attends the Christmas Day Church Service at St Mary's Church sporting a beard for the first time in public in Sandringham, England, December 25, 2008. The beard disappeared a month later.
RAF graduation
HRH Prince William, Prince Charles, The Prince of Wales and Camilla, Duchess of Cornwall stand in front of the original Chipmonk aircraft Prince Charles flew when he was training at RAF Cranwell, on the day of Prince William's RAF graduation ceremony in Cranwell, England, April 11, 2008.
Prince William completed a three month 'fasttrack' training course at the base and will move on to do a similar course with the Navy.
Prince William at RAF Cranwell
Prince William walks across the tarmac on his way to fly a Grob 115E light aircraft, known as the Tutor, while training at airbase RAF Cranwell, near Sleaford, Lincolnshire, January 17, 2008.
The prince, an army officer with the Household Cavalry's Blues and Royals, is two weeks into a four-month attachment with the RAF to help William, 25, come to grips with the service's ethos, traditions and military role.
The prince's father, Prince Charles, completed his flying training course at RAF Cranwell from March to August in 1971 and graduated that year as a Flight Lieutenant.
Concert for Diana
Their Royal Highnesses Prince William (L) and Prince Harry (R) speak on stage with Sir Elton John (far L) at the piano at the Concert for Diana at Wembley Stadium in London, July 1, 2007.
The Concert falls on the date that would have been the late princess's 46th birthday and marks 10 years since her death with an event headed by Princes William and Harry to celebrate her life.
Kate Middleton
Kate Middleton and Prince William on the day of their graduation ceremony at St. Andrew's University in St Andrew's in Scotland, June 23, 2005.
St. Andrews graduation
Prince William and his father, Prince Charles, leave William's graduation ceremony in St Andrews, Scotland, June 23, 2005.
The Prince, who earned a 2:1 class Ma in Geography, will lose the special protection set up to prevent the media from trailing him whilst he was in full-time education.
William will be conducting his first solo official engagements in New Zealand which will include ceremonies marking the anniversary of the end of World War II.
The princes
Prince Charles poses with his sons Prince William, right, and Prince Harry during the royal family's ski break at Klosters in Switzerland, March 31, 2005.
Prince William at St. Andrews
Prince William pauses in St Salvator's Quad at St. Andrews University where he is a student, November 15, 2004. The Prince is in the last year of his four-year course at the Scottish university.
Studying at St. Andrews
Prince William pauses to talk to a friend at St Andrews University, Scotland in the final year of his four-year course, November 15, 2004.
Raleigh International expedition
Prince William varnishes the outside of the local radio station in the village of Tortel, Southern Chile during his Raleigh International expedition, December 2000.
Prince William on a stamp
A London office worker licks a first class stamp carrying a picture of Prince William June 18, 2003 in London. Royal Mail issued a new set of stamps portraying the Prince ahead of his 21st birthday on June 21. Prince William is the first Royal in history to have a set of stamps issued celebrating a 21st birthday.
Prince William turns 21
Prince William blows out the candles on a birthday cake during a visit to the Anglesey Food Fair in north Wales on June 19, 2003. The Prince, will turn 21 on June 21.
Prince William in Klosters
Prince Charles and his sons William, right, and Harry, left, appear at a photocall in the Swiss village of Klosters at the start of his annual sking holiday in the Swiss Alps, March 29, 2002.
Prince William plays polo
(L to R) Britain's Prince Charles, Prince Harry and Prince William battle it out on the polo field in the Chakravarty Cup at Beaufort Polo Club, England, June 8, 2002.
Prince William in Andes
A picture taken in December 2000 shows Prince William looking at the Andes as he crosses walkways linking buildings in the village of Tortel, Southern Chile during his Raleigh International expedition.
Prince William at Highgrove
Prince William during a photocall at Highgrove, Prince Charles' residence near Tetbury in Gloucestershire, on September 19, 2000.
Princes go skiing
Prince Charles (C) talks with Prince William (L) while Prince Harry looks on during the Royal tour's official photo opportunity in Whistler, Canada March 26, 1998.
Princess Diana's funeral
(L to R) Earl Spencer, Princess Diana's brother, her two sons Princes Harry and William, and her former husband Prince Charles arrive into Westminster Abbey in London to attend the funeral ceremony of Diana, Princess of Wales, September 5, 1997.
Princess Diana's funeral
A bearer party of Welsh Guards carry the coffin of Diana, Princess of Wales, into the Westminster Abbey in London followed by (L to R) Diana's former husband Prince Charles, their son Harry, her brother Earl Spencer, her other son William and the Duke of Edinburgh, husband of Queen Elizabeth II, September 6, 1997.
Prince William at Balmoral
The Prince of Wales and his sons Prince William, 15, and Harry, 12, take an early morning walk along the banks of the River Dee on the Balmoral Estate, August 12, 1997.
Prince William and his family
Princess Diana, Prince Harry, Prince William and Prince Charles watch the parade march past as part of the commemorations of V-J Day in London, August 19, 1995.
Prince William -Eton College
Prince William, seated, flanked by his estranged parents the Prince and Princess of Wales and accompanied by his younger brother Prince Harry, signs the traditional entrance book at Eton College, west of London, for his first day at the school on September 6, 1995.
Prince William at nine
Diana, Princess of Wales, enjoys a boat ride on the Maid of Mist in Niagara Falls, Ontario, Canada with her sons Prince Harry, 7, and Prince William, 9, in October 1991.
Prince William and Princess Diana
Diana, Princess of Wales, smiles as she sits with her sons, Princes Harry, front, and William, on the steps of the Royal Palace on the island of Majorca, Spain, August 9, 1987.
Royal family portrait
The Prince and Princess of Wales, Prince Charles and Princess Diana, pose for a family portrait with their sons, Prince William, right, and Prince Harry, at the Kensington Palace in London, October 6, 1984.
Prince Harry was born on September 15, 1984. Prince William was born June 21, 1982.
Prince Harry is born
Hand-in-hand with Royal nanny Barbara Barnes, Prince William, elder son of Prince Charles and Princess Diana, leaves St. Mary's Hospital in London after visiting his new-born baby brother, Prince Henry, September 16, 1984. The newborn prince will be third in line of succession to the British Throne - after Prince William - and their father, Prince Charles.
Newborn Prince William
Prince Charles, Prince of Wales, and Princess Diana take home their newborn son Prince William, as they leave St. Mary's Hospital in London, June 22, 1982. Princess Diana's caftan-like outfit hid the post-childbirth tummy bump that is normal for any new mom. In contrast, the former Kate Middleton, in her first public appearance on July 23, 2013, after giving birth, wore a dress that did not camouflage her belly, and many women applauded her choice.
Prince Charles marries Lady Diana
Britain's Prince Charles (L) and Lady Diana, Princess of Wales, on their wedding day at St Paul's Cathedral in London, July 29, 1981.