We will always know him as Prince William, but the world is often left wondering what His Royal Highness’ last name is, especially now that he's welcomed his third baby and second son with wife Kate Middleton. So let’s get to the bottom of the mystery surrounding his surname — and answer some other 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, 92, and her spouse, now 96, 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. That said, today the royal is celebrating his 36th birthday!

When will Prince William become King of England?

While his father, 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, 35, could step into the role sooner if his dad decides to forgo the royal responsibilities once Elizabeth passes away.

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

Harry, 33, does have a chance to be king, but only after his older brother’s children, Prince George, 4, Princess Charlotte, 2, and his newborn son, who are next in line to lead the monarchy after their father. 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 does eventually become the King of England, his spouse, Kate Middleton, would be officially known as the queen 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 36 — who married William in April 2011 — said that 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!

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