The Duke and Duchess of Cambridge have named their son Louis Arthur Charles.
Kensington Palace said: "The Duke and Duchess of Cambridge are delighted to announce that they have named their son Louis Arthur Charles.
"The baby will be known as His Royal Highness Prince Louis of Cambridge."
The fifth in line to the throne was born on Monday April 23, weighing 8lb 7oz.
William and Kate's third child, the prince is the younger brother of Prince George and Princess Charlotte, and the Queen and the Duke of Edinburgh's sixth great-grandchild.