The queen's birthday is marked twice a year, once when she was born (in April) and once on the "official" birthday in June, when there is a parade.
The royal family celebrated the day on social media by sharing photos of the Queen through the years.
[Ads /]
Check out the gallery above to see how Queen Elizabeth II has changed from her days as Princess Elizabeth, to ascending the throne in 1952, to today.
[Ads /]
PHOTOS: Prince William and Princess Kate