Leap years are something of a novelty. A day added to the end of the shortest month that only happens once every four years? That’s cool. 

But why are leap years even a part of the calendar?

Fun fact about the average year: it takes the Earth approximately 365 days, 5 hours, 48 minutes, and 45 seconds to complete a full rotation around the sun. The extra day every four years helps to keep our calendar on track. Otherwise, we would lose several hours a year, and after a long period of time, our days would be out of sync.

The first leap year was actually introduced by Julius Cesar in the year 46 B.C. Cesar’s method required a leap year to occur in every year that is divisible by four. However, this caused the leap year to occur more often than necessary. The calendar would not be fixed until 1582 by Pope Gregory XIII, who introduced the Gregorian calendar that is still in use today.

There is a 1 in 1,461 chance that someone will be born on February 29. People who have this birthday are called ‘leapers.’ When it isn’t a leap year, leapers will often celebrate their birthday on February 28 or March 1.

Source: https://www.mnn.com/family/family-activities/stories/13-things-you-didnt-know-about-leap-year