Millions of people tuned in to watch the high-profile wedding take place as cameras and microphones broadcast the event worldwide.
But some of what was said between William and Kate was not picked up by the microphones, leading some to wonder what viewers might have missed.
A lip reader has analysed what was said by senior royals at the ceremony.
Ms Lannin claimed when Kate stepped up to the altar where Prince William was waiting, William apparently said: “You look lovely. You look beautiful”.
Prince Harry, who was William’s best man, had turned to the husband-to-be to warn him of Kate’s presence: “Right, here she is now!”
Ms Lannin, who has lent her lip reading expertise to police forces and various media outlets, managed to pick out some of the words between William and Kate and other members of the royal family who were also at the ceremony.
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The Duke told the Duchess that she looked "beautiful".
Ms Lannin’s transcriptions of the events were provided by Associated Press. Her opinion on what was said could not be verified.
The lip reader also revealed other touching remarks between the Duke and Duchess throughout the day.
In the wedding carriage that took the newly-weds back to Buckingham Palace, Kate told the Prince: “You look happy”.
William also appeared concerned for his wife when the two appeared on the balcony of Buckingham Palace shortly after the ceremony.
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William and Kate appeared before a huge crowd after their wedding.
The Duke turned to Kate and asked: “Alright? You’ll be okay?” The Duchess replied: “Oh I’m fine, thank you.”
Other parts of the ceremony clearly took a more humorous turn. Soon after Kate arrived at the altar, the Prince joked to her father Michael Middleton: “We’re supposed to have just a small family affair!”
This was not the case, as Britannica estimates over 1,900 guests attended the ceremony itself.
And at one point, after the couple had been wed and they entered their wedding carriage, the Queen said: “I wanted them to take the smaller carriage.”
Police estimated around one million people turned out to watch the proceedings.
However, once outside the abbey she soon admitted to Camilla, Duchess of Cornwall, that it all went “very well”.
The Metropolitan Police estimated one million people turned out to try and watch part of the parade in person on the day of the wedding. And overall, almost 1,900 guests attended the ceremony itself, Britannica reports.
Then-Prime Minister David Cameron declared the day to be a national holiday.