The Duke and Duchess of Cambridge's third and youngest child, Prince Louis, will be celebrating his fourth birthday on Saturday, April 23.
After spending two of his birthdays in a pandemic and national lockdown, Louis' fourth birthday is sure to be exciting for the young royal.
All three of William and Kate's children have a chance of becoming the monarch someday, however, they don't all have an equal stab at the throne.
As the youngest child of Prince William and Kate Middleton, here's what you need to know about Prince Louis' chance of becoming king in the future and the order of succession before him.
Could Prince Louis become king?
As the son of a future monarch, Prince Louis is likely to take up a senior role in the royal family in the future. However, he is unlikely to become king himself.
As fifth in line for the throne, the only way for Louis to become the reigning monarch is if his father and siblings all abdicate or die while holding it themselves. If a monarch abdicates or dies, then the next in line will automatically take the position.
Instead, there will be several other prestigious titles available to him, including the Duke of York if the line passes as expected. Titles that Louis can take includes others held by Prince William, among them dukedoms.
A spokesperson for etiquette expert Debretts told the Evening Standard that Louis could claim "one of his father's lesser titles", which could be either one currently held by Prince Charles or even Prince Andrew's dukedom, which would return to the monarch on his death.
What is the order of succession for the monarch?
The Royal Family line of succession has Prince Louis fifth in line.
Up next for throne, after the death of the Queen - who celebrated her 96th birthday on April 21 - is Prince Charles, followed by Prince William.
As William's eldest son, Prince George is be third in line for the throne, with Princess Charlotte currently fourth - although she will be bypassed if or when George has children.
Under ancient laws, Prince Louis may have been fourth in line due to rules that discriminated against female royals and gave male members of the family priority for the crown.
This protocol changed in 2013 with the Succession to the Crown Act, which means that Princess Charlotte's gender has no effect on her place in the line of succession.
When Prince William becomes king, George could take up the Prince of Wales title and more, while Princess Charlotte could become Princess Royal, which is a position currently held by Princess Anne.
