40 photos of Prince William through the years as he celebrates his 40th birthday

In this June 22, 1982, file photo, Britain's Prince Charles, Prince of Wales, and wife Princess Diana take home their newborn son Prince William, as they leave St. Mary's Hospital in London. 

Britain's Prince William, the 6-month old son of Prince Charles and Princess Diana, with his mother during a photo call at Kensington Palace in London, England on Dec. 22, 1982. 

Prince William holding the hands of his mother, Diana the Princess of Wales, on his arrival for the first day at his new school, Wetherby School, a pre-prep for boys, in Penbridge Square, London on Jan. 15, 1987. 

Britain's Prince Charles and Princess Diana and their sons, Princes William, right, and Harry begin a cycle ride, June 1, 1989, around the island of Tresco, one of the Scilly Isles. 

Britain's Prince William shakes hands with admirers during a stop at St. James Cathedral in Toronto, Canada, in this Oct. 27, 1991 file photo.

Britain's Princess Diana and her son Prince William applaud the Wimbledon Ladies' Tennis Championship presentations after the final, July 1, 1994. 

Prince William walks with his head bowed behind the coffin of his mother Diana, Princess of Wales, on its way to London's Westminster Abbey for a funeral ceremony, Saturday, Sept. 6, 1997. 

Britain's Prince William, wearing a Union Jack waistcoat, poses for a photo in this 2000 photo in Eton, England. 

Britain's Prince William carries out maintenance work in the village of Tortel, Southern Chile during his Raleigh International expedition in this recent but undated photo made available Monday Dec. 11, 2000. 

Britain's Queen Elizabeth II; her eldest son, Prince Charles left; and his eldest son, Prince William, pose for a photograph at Clarence House in London., June 2, 2003.

Britain's Prince William blows out the candles on a birthday cake given to him, Thursday, June 19, 2003, during a visit to the Anglesey Food Fair in North Wales. 

Britain's Prince William, left, cheers as he makes his water polo debut for the Scottish national universities squad in the annual Celtic Nations tournament against Wales and Ireland in Cardiff, Wales, Saturday, April 17, 2004. 

Britain's Prince William pauses in St Salvator's Quad at St Andrews University where he is a student in St Andrews Scotland Monday Nov. 15, 2004. 

Prince William kicks a rugby ball during a training session with some members of the British and Irish Lions players in Wellington, New Zealand, Friday, July 1, 2005. 

Britain's Prince William, marches with other graduates, during the Sovereign's parade at the Royal Military Academy, Sandhurst, near Camberley, England, Friday Dec. 15, 2006.  

Britain's Prince William gestures as he walks across the airfield at RAF Cranwell, Lincolnshire, England, Thursday, Jan. 17, 2008. 

Britain's Prince William and his girlfriend Kate Middleton walk in RAF Cranwell, England after William received his RAF wings from his father the Prince of Wales Friday April 11, 2008. 

Britain's Prince William and his fiancee Kate Middleton pose for the media at St. James's Palace in London, Tuesday Nov. 16, 2010, after they announced their engagement. 

Britain's Queen Elizabeth II is escorted by Prince William, during a visit to RAF Valley, Anglesey, Wales, where he is stationed as a search and rescue helicopter pilot, Friday April 1, 2011. 

Britain's Prince William and Kate Middleton exchange rings in front of the Archbishop of Canterbury at Westminster Abbey, London, Friday April 29, 2011. 

Britain's Prince William and his wife Kate, Duchess of Cambridge stand outside of Westminster Abbey after their Royal Wedding in London on Friday, April, 29, 2011. 

Britain's Prince William and Kate, Duchess of Cambridge holding their son, Tuesday July 23, 2013, as they pose for photographers outside St. Mary's Hospital exclusive Lindo Wing in London. 

Britain's Prince William, holds his son Prince George as they arrive at Chapel Royal in St James's Palace in London, for the christening of the three month-old Prince Wednesday Oct. 23, 2013. 

Britain's Prince William, the Duke of Cambridge walks, with an East Anglian Air Ambulance (EAAA) in the background, as he begins his new role, at Cambridge Airport, Cambridge, in England, Monday July 13, 2015. 

Britain's Queen Elizabeth II, left, attends the annual Festival of Remembrance with Prince Philip, Prince William, right and Kate, the Duchess of Cambridge, in London, England, Saturday, Nov. 7, 2015. 

Britain's Prince William, background center, Kate, the Duchess of Cambridge, background and Prince Harry take part in a relay race, during a training event to promote the charity Heads Together, in London, Sunday, Feb. 5, 2017. 

FILE From left, Britain's Charles, Prince William and Prince Harry attend a ceremony marking the 100th anniversary of the Battle of Vimy Ridge, in Vimy, France, Sunday, April 9, 2017. 

Britain's Prince Harry, left, reacts as he walks with Prince William as they arrive for his wedding to Meghan Markle at St. George's Chapel, in Windsor, England, Saturday, May 19, 2018. 

Britain's Prince William delivers a speech, during the launch of the Heads Up Weekends, in London, Wednesday, Feb. 5, 2020. 

Prince Harry, left, and Prince William stand during the unveiling of a statue of their mother Princess Diana, on what would have been her 60th birthday, in Kensington Palace, London, Thursday July 1, 2021. 

Britain's Prince William, left and Prince Harry unveil a statue of their mother Princess Diana, on what would have been her 60th birthday, in the Sunken Garden at Kensington Palace, London, Thursday July 1, 2021. 

Britain's Prince William delivers a speech at the Tusk Conservation Awards in London, Monday Nov. 22, 2021.

Prince William salutes veterans on Horse Guards Parade during the Remembrance Sunday service at the Cenotaph, in Whitehall, London, Sunday Nov. 14, 2021. 

Britain's Prince William, left and Kate, the Duchess of Cambridge attend the 'Royal Carols - Together At Christmas', a Christmas carol concert hosted by the duchess at Westminster Abbey in London, Wednesday Dec. 8, 2021. 

Britain's Prince William and Kate, Duchess of Cambridge attend the 1st Battalion Irish Guards' St. Patrick's Day Parade at Mons Barracks, Thursday March 17, 2022 in Aldershot, England. 

Britain's Prince William sits by the The Imperial State Crown in the House of Lords Chamber, during the State Opening of Parliament, in the Houses of Parliament, in London, Tuesday, May 10, 2022. 

Britain's Prince William visits at the Heart of Midlothian Football Club, in Edinburgh, Scotland, Thursday May 12, 2022. 

Britain's Prince William, President of The Royal Marsden NHS Foundation Trust, leaves after visiting to learn about the innovative work that is currently carrying out to improve cancer diagnosis, in London, Tuesday, May 24, 2022. 

Britain's Prince William speaks during the Platinum Jubilee concert taking place in front of Buckingham Palace, London, Saturday June 4, 2022, on the third of four days of celebrations to mark the Platinum Jubilee. 

Kate, Duchess of Cambridge, Prince Louis, Princess Charlotte, Prince George, and Prince William watch from the balcony of Buckingham Place after the Trooping the Color ceremony in London, Thursday, June 2, 2022.