Look at those chubby cheeks!
"The Duke and Duchess of Cambridge are very pleased to share two photographs of Princess Charlotte and Prince Louis, taken by The Duchess at Kensington Palace," the caption for the image showing just Prince Louis read. "This image of Prince Louis was taken by The Duchess of Cambridge at Kensington Palace on 26th April. The Duke and Duchess would like to thank members of the public for their kind messages following the birth of Prince Louis, and for Princess Charlotte's third birthday."
Along with the photo, the family also shared an adorable image of Prince Louis and Princess Charlotte, showing her kissing Louis on the forehead.
The new baby is named Louis Arthur Charles, and was born on Monday morning, April 23, at St. Mary's Hospital in London.
This is the third child for The Duke And Duchess of Cambridge, after 4-year-old Prince George and 2-year-old Princess Charlotte. Additionally, he is the second son of the couple, and will be fifth in line for the throne.
Prince William signed the birth certificate of his third child at Kensington Palace, eight days after the little prince was born. The certificate, made public, shows the royal baby's full name and title: His Royal Highness Prince Louis Arthur Charles of Cambridge. Just like his parents and his older siblings, Prince Louis does not have a last name.
As Brits and the world-alike anxiously awaited the big reveal, many began placing bets on what the little one's name would be, with a large betting company based in the U.K. called Ladbrokes having reported that Arthur was the top name, per their top bets. Other contenders included James, Thomas, and Henry.
Though some thought the name was ironic given that Louis was also the name 18 kings from across the Channel, it turns out that the name Louis holds a lot of significance in the Royal Family.
William, along with Louis' older brother, Prince George, share the middle name Louis, which is believed to be a tribute to Louis Mountbatten.
Lord Mountbatten, Prince Philip's uncle, played a key role in the relationship between Queen Elizabeth and Prince Philip, William's grandparents (Louis' great-grandparents). He was also closely related to the royal family by way of his great grandmother, Queen Victoria.
At the time of Mountbatten's death in 1979, he was close with a young Prince Charles, who took his death very hard. Princess Diana reportedly knew the impact Mountbatten had on Charles, which is said to be what first attracted Charles to her.