Leap year is a year in the Gregorian calendar that contains an extra day, making the leap year 366 days long instead of 365 days long. The extra day added into a leap year is always February 29th. Leap years generally occur every four years, unless that year may be evenly divided by 100 but not evenly divided by 400. Leap years are necessary because a solar year is slightly longer than 365 days and over time, the calendar will become out of sync with the natural seasons if adjustments are not made. The term leap year comes from the fact that normally, fixed holidays advance one weekday every year, but in a leap year holidays leap ahead an extra weekday.
Examples
This year’s leap day, Feb. 29, 2016, may mean that someone born on Feb. 29, 1916, could jokingly claim they’re turning 25-years-old rather than 100. (The Christian Science Monitor)
The ninth episode of season six has the characters celebrate Leap Day in an alternate universe where Feb. 29 is a real holiday with its own mythology — a place where a Santa-like figure named Leap Day William takes away the tears of children and gives them candy, and where a Leap Day film starring Jim Carrey and Andie MacDowell is enjoyed as a classic. (The Standard Examiner)
Feb. 29 is more like a catch-up day than a leap day, however, as the astrophysicist Neil deGrasse Tyson recently told our Grace Notes columnist, James Barron. (The New York Times)
Australian men with long-term girlfriends be warned, 20 per cent of women support the tradition which says they can propose during a leap year. (The Sydney Morning Herald)
For centuries, trying to sync calendars with the length of the natural year caused confusion—until the concept of leap year provided a way to make up for lost time. (National Geographic Magazine)