Prince George will need to choose his surname soon.
The four-year-old royal is heading to nursery in September and his parents - Prince William and Duchess Catherine - will need to pick a surname for him so he can register with his school when term time starts.
It is likely that the family will go for Mountbatten-Windsor but could choose Wales or Cambridge.
Explaining its origin on the official Royal website, a post reads: "The Royal Family name of Windsor was confirmed by The Queen after her accession in 1952. However, in 1960, The Queen and The Duke of Edinburgh decided that they would like their own direct descendants to be distinguished from the rest of the Royal Family (without changing the name of the Royal House), as Windsor is the surname used by all the male and unmarried female descendants of George V.
"It was therefore declared in the Privy Council that The Queen's descendants, other than those with the style of Royal Highness and the title of Prince/Princess, or female descendants who marry, would carry the name of Mountbatten-Windsor. The effect of the declaration was that all The Queen's children, on occasions when they needed a surname, would have the surname Mountbatten-Windsor."
However, it is likely that Prince George - whose name was announced as George Alexander Louis when he was born - will have the Mountbatten-Windsor name unless Prince Charles decides to change the family surname.
The post adds: "For the most part, members of the Royal Family who are entitled to the style and dignity of HRH Prince or Princess do not need a surname, but if at any time any of them do need a surname (such as upon marriage), that surname is Mountbatten-Windsor.
"Unless The Prince of Wales chooses to alter the present decisions when he becomes king, he will continue to be of the House of Windsor and his grandchildren will use the surname Mountbatten-Windsor."