The rarest birthday in the world is February 29th, also known as Leap Day.
This is because it only occurs once every four years, during leap years.
While there are other rare birthdays, like December 31st or January 1st, these dates occur annually.
However, February 29th only comes around every four years, making it the most unique and uncommon birthday on the calendar.
People born on Leap Day have the option of celebrating their birthday on either February 28th or March 1st during non-leap years.
