Prince William and his wife Kate, both 31, are expecting their first child, to be third in line for the throne. Here are some highlights of their lives and of the royal pregnancy:
-Sept. 2001: Prince William and Kate Middleton meet at St Andrews University in Scotland where they are both studying art history.
-Christmas 2003: The pair reportedly become a couple after sharing a house together with two friends. In March they are pictured together on a skiing holiday in Switzerland.
-Nov. 16, 2010: William and Kate's engagement is announced by Clarence House officials. The prince proposed to Kate while on a private holiday to Kenya the previous month.
-April 29, 2011: The pair wed in a lavish ceremony at London's Westminster Abbey. William is made the Duke of Cambridge by his grandmother, Queen Elizabeth II, and Kate becomes the Duchess of Cambridge.
-Dec. 3, 2012: The palace announces that Kate is pregnant and being treated in hospital for acute morning sickness. Kate is discharged from the hospital after three nights, telling reporters she is feeling "much better." The palace later announces that the bay is due in July.
-Feb. 5: The couple holiday on the Caribbean island of Mustique with Kate's parents.
-March 5: Kate apparently lets slip that she is expecting a daughter on a solo visit to Grimsby. Accepting a teddy bear from a member of the public, she apparently replies: "Oh, is this for our d...? Thank you so much." The possible slip of the tongue prompts a wave of betting on a royal daughter.
-March 17: Kate tells a soldier at a St Patrick's Day parade that they do not know the sex of the child, but says she would like a boy and William a girl.
-March 20: Kate given a "Baby on board" badge when she joins the Queen and Prince Philip at Baker Street underground station to mark the 150th anniversary of the Tube.
-May 11: Kate and William attend William van Cutsem and Rosie Ruck Keene's wedding in Oxfordshire, England. The pair reportedly take to the dance floor despite Kate being seven months pregnant.
-June 4: William and Kate return to their wedding venue at Westminster Abbey when they join the royal family for a service marking the 60th anniversary of the Queen's Coronation at Westminster Abbey.
-June 13: Kate carries out her final solo engagement before going on maternity leave when she names a new cruise liner - the Royal Princess - in Southampton.
-June 15: The Duchess makes her last scheduled public appearance before the birth at the Trooping the Color parade.
-June 19: It is confirmed Kate is planning to give birth at the private Lindo Wing of St. Mary's Hospital in Paddington, where Princess Diana gave birth to William and Prince Harry. It is reported Kate is hoping for a natural birth.
-July 22: Kate and William arrive at the hospital in the early morning and Kensington Palace confirms that Kate is in labor.
LONDON - Champagne bottles popped and shouts of "Hip! Hip! Hooray!" erupted outside Buckingham Palace on Monday as Britain welcomed the birth of Prince William and his wife Kate's first child, a boy who is now third in line to the British throne.
Hundreds of Britons and tourists broke into song and dance outside the palace gates as officials announced that the future king was born at 4:24 p.m., weighing 8 pounds, 6 ounces (3.75 kilograms), at central London's St. Mary's Hospital - the same place where William and his brother Harry were born three decades ago.
The imminent arrival of the royal baby was the subject of endless speculation on social media and was covered for days on live television around the world, but in the end the royal family managed to keep it a remarkably private affair.
In line with royal tradition, a terse statement announced only the time of birth, the infant's gender and that mother and child were doing well. It gave no information about the baby's name, and officials would say only that a name would be announced "in due course."
"Her Royal Highness and her child are both doing well and will remain in hospital overnight," it said. William also issued a brief statement, saying "we could not be happier."
Officials said William, who was by his wife's side during the birth, would also spend the night in the hospital.
William's press aides had talked about preserving Kate's "dignity" throughout the pregnancy, and the way the birth was handled showed that the palace's impressive stagecraft could give the royals a bubble of privacy even in the age of Twitter and 24-hour news broadcasts.
Just before 6 a.m., 31-year-old Kate, also known as the Duchess of Cambridge, entered the hospital through a side door, avoiding the mass of journalists camped outside. Officials did not announce she was hospitalized until more than an hour later.
Later, as the world media gathered outside filled hours of airtime with speculation, the baby's birth went unannounced for nearly four hours, allowing the royal couple the private time they needed to act like a regular family - a goal 31-year-old William has cherished.
He was able to tell his father, Prince Charles, and grandmother, Queen Elizabeth II, about the birth and enjoy his wife's company without having to cope with the overwhelming media and public desire for information.
By nightfall, the public still knew very few details, but most people seemed satisfied with the day's events. London's landmarks, including the London Eye, lit up in the national colors of red, white and blue, and the city had a party atmosphere unmatched since last summer's Olympics.
Outside the hospital, a man dressed as a town crier in traditional robes and an extravagant feathered hat shouted the news and rang a bell.
A car carrying the announcement drove from the hospital to the palace, where the news was greeted with shrieks of "It's a boy!" and strains of "For He's a Jolly Good Fellow." A large crowd rushed against the palace fences to catch a glimpse of an ornate, gilded easel displaying a small bulletin formally announcing the news.
The framed sheet of paper became the target of a thousand camera flashes as people thrust their smartphones through the railings. Hours after the initial announcement, crowds were still surging forward to get near the easel. Some placed presents and bouquets in front of the palace, while others waved Union Jack flags and partied on the streets to celebrate.
"It's a crazy atmosphere. Everyone is getting very excited," said Andrew Aitchison. "It's great to be part of history, to say we were here and saw it all happen."
More celebrations are expected Tuesday, including gun salutes by royal artillery companies to honor the birth. Riders in uniform will trot past the palace to Green Park, where six field guns will fire 41 blank rounds.
Prince Charles spoke of his joy and pride in becoming a grandparent for the first time.
"It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy," Prince Charles said in a statement. "Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time, and we are eagerly looking forward to seeing the baby in the near future."
It could be some time before the baby's name is made public. When William was born, a week passed before his name was announced. Charles' name remained a mystery for an entire month.
The royal birth at St. Mary's Hospital recalled that of the baby's father, William, in 1982. Many remember the moment when he was carried out in Princess Diana's arms with proud father Prince Charles at their side.
The media will now continue to camp outside the hospital to capture a similar photograph for William and Kate's son, who is third in line to the throne behind Charles and William.
The baby's gender had been of particular interest because the prospect of Kate's pregnancy had prompted a change in the laws of succession to ensure that a daughter would not be passed over for the crown by a younger brother.
No one can tell what political and personal changes the intervening years will bring, but the baby can be expected to become the head of state of 16 countries, including Britain, Australia and Canada. The child will also eventually become Supreme Governor of the Church of England.
The little prince represents a living link to Britain's imperial history as the great-great-great-great-great-grandchild of Queen Victoria, who ruled at the peak of British power.
Many Britons had hoped that William and Kate would start a family shortly after their gala 2011 wedding, which drew a global television audience in the hundreds of millions.
The couple waited, however, until William was nearly finished with his military work as a search-and-rescue helicopter pilot based at an air base in a remote island off the coast of Wales.
That allowed Kate to ease into royal life, and to become more comfortable in the spotlight, before becoming a parent. It also allowed her to play a supporting role during Queen Elizabeth II's Diamond Jubilee celebrations last summer.
The first months of her pregnancy were not easy, and she was hospitalized in early December with acute morning sickness that left her weak and dehydrated. She seemed to recover her stamina fairly quickly and made a series of public appearances until the final weeks, drawing praise for her poise and good cheer.
The royal couple and their newborn are expected to spend much of their time in the coming years in renovated quarters at Kensington Palace, where William and Harry also spent much of their childhood.
Royal officials say Kate and William will try to give their child as normal an upbringing as possible, a challenging goal in an age when the British royals are treated as major world celebrities.
"He'll have to be protected all the time," said Edward Bentley, from near London. "But they'll make him seem normal and connected to the public for sure."