What is a leap year?
A leap year is a year with 366 days instead of 365, with an extra day, February 29, added to keep the calendar in line with Earth's orbit around the Sun.
Earth takes about 365.2422 days to orbit the Sun. A 365-day calendar would fall behind by almost six hours each year, so every four years an extra day is added. The rule in the Gregorian calendar is that a year is a leap year if it is divisible by 4, except century years, which must be divisible by 400.
That means 2024 and 2028 are leap years, and 2000 was a leap year, but 1900 was not and 2100 will not be. This system was introduced by Pope Gregory XIII in 1582 to correct errors in the older Julian calendar, which had added too many leap days.
Leap day birthdays
People born on February 29 are called leaplings or leapers. In common years, they usually celebrate on February 28 or March 1. The chance of being born on a leap day is about 1 in 1,461. The next leap day will be February 29, 2028.
Did You Know?
According to an Irish tradition, women could propose marriage to men on February 29, a custom said to date back to Saint Brigid and Saint Patrick.