We will always know him as Prince William, but the world is often left wondering what the Duke of Cambridge’s last name actually is. This especially now that brother Prince Harry welcomed a son named Archie with Meghan Markle on Monday, May 6.

Let’s get to the bottom of the mystery surrounding William’s surname, answering some of your burning questions about the handsome prince!

What is Prince William’s last name?

Although the British Royal Family often nixes their surname altogether, William’s is Mountbatten-Windsor, along with any descendant of Queen Elizabeth “other than those with the style of Royal Highness and the title of Prince/Princess, or female descendants who marry.”

In case you were curious about the origin of Mountbatten-Windsor, the Windsor portion comes from Elizabeth’s father, King George V, who chose the name in 1917 during World War I. Prior to that, the royals had not adopted a last name, but distinguished themselves by the house or dynasty to which they belonged.

The first part of William’s last name comes from Elizabeth’s husband, Prince Philip, who was born with the surname Mountbatten. The queen, 93, and Philip, 97, decided that it would be best to combine the two names to separate their immediate family from the rest of their royal relatives.

When is Prince William’s birthday?

Prince William’s birthday is June 21. The duke’s children all have birthdays a few close to that date: son Prince George, 5, was born on July 22; daughter Princess Charlotte, 3, was born on May 2, and son Prince Louis, 1, was born on April 23.

When will Prince William become King of England?

While dad Prince Charles has been first in line to inherit the throne for more than 65 years (longer than any other heir in British history!), William, 36, could step into the role sooner if Charles decides to forgo the royal responsibilities once Elizabeth passes away.

What about Prince Harry? Does he have a shot at being king?

Harry, 34, does have a chance to be king, but only after Charles, William, and all of William’s kids. Harry is actually sixth in line to the throne, meaning Archie is seventh. So, yeah, that’s a super long wait…

royal family - getty images

Can Prince William’s wife, Kate Middleton, ever become the Queen of England?

When William eventually becomes King of England, wife Kate Middleton would be officially known as the queen consort. Philip is Queen Elizabeth’s prince consort. Interesting, right?

How did Prince William and Kate Middleton meet?

Will and Kate’s love story began in 2001, when they were both attending school at the University of St. Andrews in Scotland. The adorable duo — who were both studying art history at the time — lived in separate quarters of St. Salvador’s Hall, a co-ed residence hall.

During a 2010 interview with The Telegraph, Kate, now 37 — who married William in April 2011 — said she “went bright red and scuttled off, feeling very shy” after their first encounter.

william and kate - getty images

For his part, William was intrigued from the get-go. “We just spent more time together, we had a good giggle and realized we shared some interests,” the now-dad-of-three once said of their first few years of dating. “She has a normal sense of humor which is really good for me because I’ve got a dead sense of humor, and things happened.” And the rest is history!