LONDON - With a smile that lit up TV screens around the world, Kate Middleton married Prince William in a union that promised to revitalize the British monarchy. A million people roared their approval as the royal couple then paraded through London in an open carriage.

Britain's Prince William and his wife Kate, Duchess of Cambridge kiss on the balcony at Buckingham Palace after their wedding in Westminster Abbey, in central London April 29, 2011. [Photo/Agencies]

Even knowing that an immense television audience was tuning in to watch, the couple managed, at times, to appear in their own private world Friday, both at Westminster Abbey and on the balcony of Buckingham Palace.

William whispered to Kate, who radiated contentment and joy, as they pledged their lives to one another at the church with the simple words "I will."

After a ceremonial tour around London, they then delivered two -- not one -- sweet, slightly self-conscious kisses on the balcony, with William blushing deeply at the highly anticipated event. Within moments, a flyby of vintage and modern Royal Air Force planes roared overhead.

For much of the world, the wedding was a dramatic introduction to Middleton's beguiling star power. Despite the pressure, the 29-year-old carried the day with an easy smile, youthful exuberance and a sense of decorum that matched the event.

After the ceremony, Middleton curtsied easily before her new grandmother, Queen Elizabeth II, comfortably sharing the stage with the woman who has reigned since 1952. For many Britons, it was the first time since the queen's youth that they have seen such a composed, beautiful royal bride.

The sighting of Middleton's wedding gown -- the biggest secret of the day -- prompted swoons of admiration as she stepped out of a Rolls-Royce with her father at the abbey. Against all odds, the sun broke through steely gray skies at precisely that moment.

Her ivory-and-white satin dress -- with its plunging neckline, long lacy shoulders and sleeves and a train over 2-meters (yards) long -- was designed by Sarah Burton at Alexander McQueen. Middleton's hair was half-up, half-down, decorated with dramatic veil and a tiara on loan from the queen. Her dramatic diamond earrings were a gift from her parents.

"It's a dream," said Jennie Bond, a leading British monarchy expert and royal wedding consultant for The Associated Press. "It is a beautiful laced soft look, which is extremely elegant. She looked stunning."

The structured dress, which emphasized Middleton's slim figure, reminded some of the wedding dress worn by a princess from another era, the late Grace Kelly of Monaco.

William, second-in-line to the throne after his father, Prince Charles, wore the scarlet tunic of an Irish Guards officer, reinforcing his new image as a dedicated military man.

The couple's first royal wedding present came from the queen: the royal titles of the duke and duchess of Cambridge.

A flood of well-wishers -- as well as some protesters -- packed central London, especially around Buckingham Palace, Westminster Abbey and other landmarks beginning at dawn, despite cool temperatures and the threat of rain. Cheers erupted as huge television screens began broadcasting at Trafalgar Square and Hyde Park.

"Will, it's not too late!" read one sign held aloft by an admirer dressed as a bride.

The Metropolitan Police estimated the crowd peaked at one million along the route, with around 500,000 people in and around The Mall trying to catch a glimpse of the couple's kiss.

Maid of honor Pippa Middleton wore a simple column dress and naturally styled hair, while best man Prince Harry was dressed in formal military attire. The flower girls, in cream dresses with full skirts and flowers in their hair, walked down hand-in-hand with Pippa.

The iconic abbey was airy and calm, the long aisle leading to the altar lined with maple and hornbeam trees as light streamed in through the high arched windows. The soft green trees framed the couple against the red carpet as they walked down the aisle, having recited their vows without stumbling before Archbishop of Canterbury Rowan Williams.

The royal couple smiled broadly as they were driven to Buckingham Palace in the open-topped State Landau, a carriage built in 1902, escorted by four white horses and followed by scarlet-clad troops on horseback.

Later in the afternoon, William and Middleton delighted the crowds outside of Buckingham Palace by going out for a spin in a dark-blue Aston Martin Volante convertible festooned with ribbons, bows and balloons and bearing the ceremonial license plate "JU5T WED."

It drove down London's Mall for a couple minutes before pulling in to Clarence House, drawing cheers from the lingering crowd.

The Aston Martin has been owned since 1969 by Prince Charles, an ardent environmentalist who had the car converted so that it could run on bioethanol made from the waste matter generated by English wine production.

It was accompanied by a search-and-rescue helicopter in a special flyby. William is a serving search-and-rescue pilot on the island of Anglesey in Wales.

The palace was holding two parties, one hosted by the queen for 650 guests, and an evening dinner dance for 300 close friends. The queen and her husband have promised to go away for the evening, leaving the younger royals free to party the night away -- and Harry to make his best man's speech away from his grandparents' ears.

British singer Ellie Goulding, 24, is reportedly going to perform, and rumors have it that Harry has even planned a breakfast for those with the stamina to dance all night.

Plumage of Amazonian variety filled the cavernous abbey as some 1,900 guests filed in, the vast majority of women in hats, some a full two feet (half a meter) across or high. Several looked like dinner plates, and one woman wore a bright red fascinator that resembled a flame licking her cheek. A BBC commentator noted there were some "very odd (fashion) choices" walking through the abbey door.

Most men, however, looked elegant and suave in long tails, some highlighted by formal plaid pants and vests. Others wore military uniforms.

The queen, of course, wore a soft yellow hat and coat dress, just like the bookies had predicted.

All the details -- the wedding dress, her hair, their titles, the romantic kiss on the balcony, the honeymoon -- were finally being answered. But the biggest question won't be resolved for years: Will this royal couple live happily ever after?

Will their union endure like that of William's grandparents -- Queen Elizabeth II and Prince Philip, now in its 64th year -- or crumble in a spectacular and mortifying fashion like that of his own parents, Prince Charles and Princess Diana?

Recent history augurs badly: The first marriages of three of the queen's four children ended in divorce. But William and Kate seem to glow with happiness in each other's company, and unlike Charles and Diana they've had eight years to figure out that they want to be together.

Still, the fate of their marriage depends on private matters impossible for the public to gauge, since any wedding is fundamentally about two people. Will their lives together, starting with such high hopes, be blessed by good fortune, children, good health, productive work?

Much will depend on whether 28-year-old William and 29-year-old Kate can summon the things every couple needs: patience, love, wit and wisdom. But they face the twin burdens of fame and scrutiny. Money, power, beauty -- it can all go wrong if not carefully nurtured.

These are the thorny issues upon which the fate of the monarchy rests, as the remarkable queen, now 85, inevitably ages and declines.

Hundreds of street parties were under way as Britons celebrated the heritage that makes them unique -- and overseas visitors came to witness those traditions.

Brenda Hunt-Stevenson, a 56-year-old retired teacher from Newfoundland, Canada, said there was only one thing on her mind. "I want to see that kiss on that balcony. That's going to clinch it for me. I don't care what Kate wears. She is beautiful anyway."

The celebration was British to the core, from the freshly polished horse-drawn carriages to the sausages and lager served at street parties. Some pubs opened early in the morning, offering beer and English breakfasts -- sausages, beans, toast, fried eggs and bacon.

Police said they had arrested 43 people for offenses including drunkenness, breach of peace, and theft.

The festivities reflected Britons' continuing fascination with the royal family, which despite its foibles remains a powerful symbol of unity and pride.

"It's very exciting," Prime Minister David Cameron said. "I went on to the mall last night and met some people sleeping on the streets. There's a sense of excitement that you can't really put a word to ... it's a chance to celebrate."

Others disagreed.

John Deery, 45, from west London, described the royal family as "unjustifiable" in the modern day and age.

"What I want is a democratic alternative to the monarchy," he said.

A number of famous people were left off the guest list, including US President Barack Obama and Britain's last two prime ministers, Tony Blair and Gordon Brown of the Labour Party, which is not as strong a backer of the monarchy as the governing Conservatives. Some critics call that a snub which could resonate for years among Labour voters.