Prince William, the Duke of Cambridge, is second in line to the throne.
In 2011 he and Catherine Middleton were married, and the duchess gave birth to the couple's first child, Prince George, at 16:24 BST on 22 July 2013.
Royal commentator Margaret Holder said she thought the marriage would give Prince William what he really wanted - a warm, cosy, family life.
Born at 21.03 BST on 21 June 1982, weighing just over 7lbs (3kg), Prince William Arthur Philip Louis was soon introduced to the public in his first official photographs.
Baby William was christened by the then Archbishop of Canterbury, Dr Robert Runcie, on the Queen Mother's 82nd birthday on 4 August 1982, in the Music Room at Buckingham Palace.
He went to Jane Mynors' nursery school in London in September 1985 and two years later started at Wetherby School.
The prince moved to Ludgrove School in Berkshire in September 1990 where he stayed until entering Eton in 1995.
During their time at school Prince Charles struck a deal with the press whereby William and his brother Harry were left alone in return for limited access at press and photo calls.
William left Eton with A-levels in geography, biology and history of art as well as 12 GCSEs.
During a gap year between school and university he went to Mauritius, spent time in Africa, trekked with the Army in Belize and worked as a Raleigh International volunteer in Chile.
But it was, he says, his short stint working as a labourer on a dairy farm in south-west England that he enjoyed the most.
As a schoolboy, William witnessed the breakdown of his parents' marriage, followed by the tragic death of his mother Princess Diana in a car crash in Paris, in 1997.
Many people remember him walking behind the cortege of his mother at her funeral in Westminster Abbey in 1997, accompanied by his brother, father, grandfather and uncle.
The duke has taken on his mother's legacy by getting heavily involved with charities, working to help survivors of the December 2004 tsunami and to protect endangered species in Africa.
He is also patron of the young people's homelessness charity Centrepoint - as was Diana.
Having become president of the Football Association, the duke teamed up with David Beckham in 2010 to spearhead England's unsuccessful bid to stage the 2018 World Cup.
As an undergraduate at St Andrews University in Fife, he met and shared a cottage with fellow student Catherine Elizabeth Middleton.
William graduated in 2005 with a class 2:1 degree in geography, making him one of the most academically successful royals.
He then chose to join his younger brother Harry for officer training at the Royal Military Academy at Sandhurst.
The start of his military career, in early 2006, came after several months' work experience, during which he shadowed financial staff in the City of London, acted as a "rescue novice" with a mountain rescue team and learned about land estate management.
While at Sandhurst, William also carried out his first solo engagements, attending ceremonies in Wellington and Auckland on behalf of the Queen to mark the anniversary of the end of World War II.
After graduating, he served as an officer in the Household Cavalry Blues and Royals before entering training with the RAF and Royal Navy.
In April 2008, William was presented with his RAF wings by his father - and looking on proudly was his girlfriend Catherine, firmly back in his life after a split the previous year.
Unlike his brother Harry, William was never going to be sent to the front line in Afghanistan, but he put an end to speculation that he might quit the armed forces to be a full-time royal by announcing his plan to become a search and rescue pilot.
The prince called it "a perfect opportunity for me to serve in the forces operationally, while contributing to a vital part of the country's emergency services".
'Chance to back out'
William and Kate were granted some privacy during their time as students, but after graduating, that period of calm ended - and Catherine, without any security, bore the brunt.
Former royal press secretary Dickie Arbiter said the harassment of her by photographers in 2006 and 2007 was akin to the treatment of William's mother.
The duke has often been angered by the attention, making it clear via his aides that more than anything he wanted her to be left alone.
In 2012, the couple took legal action against a French magazine that published topless pictures of the duchess, taken during a private holiday.
Asked after their engagement was announced why he had waited so many years to propose, William said: "I wanted to give her a chance to see in and to back out if she needed to before it all got too much."
After more than seven years in the military the duke is leaving the military to focus on royal duties and charity work.
He is expected to work closely over the next year with the Royal Foundation of The Duke and Duchess of Cambridge and Prince Harry.
Flt Lt William Wales spent three years as an RAF search and rescue pilot with RAF Valley on Anglesey, north Wales, and the couple are expected to move from their cottage on the island to an apartment in Kensington Palace.
Whilst based at RAF Valley he took part in 156 operations and rescued 149 people, qualifying as a helicopter captain in 2012.
In 2012 he was deployed to the Falkland Islands, prompting a diplomatic row with Argentina, which claims the islands which it calls the Malvinas.
A Kensington Palace spokesman said he would continue his charitable activities relating to children and young people, and former and serving members of the armed forces, and expand his conservation work, focussing on endangered species.
But royal officials have also said the next year will be "transitional" for Prince William, who will not become a "full time royal" at this stage.