In their first year in 2001, William and Kate lived a few doors apart at St Salvator's hall of residence at St Andrews in Fife and became friendly, socialising together and playing tennis.
She captured his attention in March 2002 when the prince forked out £200 for a front-row seat for the fashion show where Kate appeared in a see-through lace dress which revealed her black underwear.
Kate, who is five months older than William, was credited with persuading him to continue his studies when he found it difficult to settle and considered quitting in his first year.
They began sharing a four-bedroom Edwardian townhouse at the start of their second year.
At the time Miss Middleton was dating another student, Rupert Finch.
Kate and William were joined by two friends, and the following year the four students moved into a secluded rented cottage outside the town.
Kate was one of a close coterie of friends invited to William's 21st birthday party at Windsor Castle.
The pair shared a love of sport and the outdoor life and they were rumoured to have become an item around Christmas 2003.
William said in his engagement interview: "When I first met Kate I knew there was something very special about her."
He spoke about how their relationship developed: "We just spent more time with each other, had a good giggle, had lots of fun and realised we shared the same interests and just had a really good time. She's got a really naughty sense of humour."
Kate admitted that she was "very shy" when meeting William and went bright red.
The first confirmation that the flatmates were romantically linked came when they were pictured on the slopes of the posh Swiss ski resort Klosters in March 2004.
Kate's acceptance as William's girlfriend by "The Firm" was seen as complete a year later when she was pictured again at Klosters alongside William and his father.
William, irritated they had been snapped together on a private break, later declared: "I'm only 22 for God's sake. I am too young to marry at my age. I don't want to get married until I'm at least 28 or maybe 30."
Their relationship flourished during romantic weekends alone on the Queen's Balmoral estate, at a cottage given to William and his younger brother Prince Harry as a bolthole, and on holiday in Kenya.
But Kate kept her distance from major royal events.
The couple were cautious. They were said to avoid acting affectionately in front of friends, both keenly aware of the media interest in their relationship.
In October 2005, Kate's legal team, Harbottle & Lewis, who also represent the Prince of Wales, wrote to newspaper editors appealing to the press to leave her and her family alone.
She joined fashion chain Jigsaw, owned by friends of her family, in 2006 as an accessories buyer.
She then left her job to work for her parents' business.
In December 2006, she turned up to watch William graduate as an Army officer at Sandhurst.
It was the first time she had been at a high-profile public event attended by the monarch and senior royals as William's guest and it intensified speculation the pair would walk up the aisle.
A lip-reading expert revealed Kate had declared as she spotted William in military dress: "I love the uniform. It's so, so sexy."
Yet within months the prince was drawn away to his life in the Army and in April 2007, it was confirmed the pair had split.
Kate was spotted on nights out in London, looking happy and relaxed.
She handled the split with grace, and kept William's confidence.
Just months later in July 2007, she was a VIP guest in the royal box for William and Harry's Concert for Diana in memory of their mother, and was seen canoodling with William at the after-show party.
William revealed, when their engagement was announced, that having some space helped their relationship, while Kate said it made her a "stronger person".
After they were reunited, Kate appeared at a number of high-profile official events including William's RAF "wings" presentation ceremony in April 2008.
At the wedding of their friends, showjumper Harry Meade and Rosie Bradford, in October 2010, the pair, sporting healthy tans from a break in Kenya, strolled happily side by side.
They were secretly engaged, with William having popped the question with his late mother's engagement ring as they holidayed at Lake Rutundu.
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