We take a look back at photos of the prince, from his schoolboy years, through his love story with the Duchess of Cambridge, to his latest role as a father.
9. Becoming a father
The Duke and Duchess of Cambridge leaving the Lindo Wing of St Mary's Hospital in London, with their newborn son, Prince George of Cambridge on July 23, 2013
10. Invictus Games
Duke of Cambridge, the Duchess of Cornwall and the Prince of Wales at the opening ceremony of the Invictus Games at the Queen Elizabeth Olympic Park in September, 2014
11. Clap for Carers
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge and their children taking part in the nationwide Clap for Carers in 2020 for the BBC's The Big Night In with Children In Need and Comic Relief