William and Kate have become the new Prince and Princess of Wales, King Charles has said.
It means William is following in his father's footsteps, and Kate has become the first person since Diana, Princess of Wales, to use the title which Diana held when she was married to Charles.
In a speech to the nation, the King said that "with Catherine beside him, our new Prince and Princess of Wales will, I know, continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given".
Catherine "appreciates the history associated with this role, but will understandably want to look to the future as she creates her own path", a source said.
"The couple is focussed on deepening the trust and respect of the people of Wales over time," they said, adding the couple would approach their new roles "in the modest and humble way they've approached their work previously".
Welsh First Minister Mark Drakeford said King Charles had enjoyed a "long and enduring friendship" with Wales, and the country "looked forward to deepening our relationship with the new Prince and Princess of Wales".
Queen Consort, Camilla, was also technically the Princess of Wales when she married Charles in 2005 but never used the title because of its association with Diana, who died in a car crash in 1997.
Diana was stripped of her HRH style and her title was changed to Diana, Princess of Wales following her divorce the year before she died.
As well as taking the Prince of Wales title previously held by the King, William has assumed his Scottish titles and succeeded him as the Duke of Cornwall.
Therefore, William and Kate are also the Duke and Duchess of Cornwall, and the Duke and Duchess of Rothesay in Scotland.
King Charles said: "I am proud to create him Prince of Wales, Tywysog Cymru, the country whose title I have been so greatly privileged to bear during so much of my life and duty."
He added: "I want also to express my love for Harry and Meghan as they continue to build their lives overseas."