Leap Year Day

A leap year is a calendar year that has one extra day (or, in the case of a lunisolar calendar, one extra month) in comparison to a common year. It is sometimes referred to as an intercalary year or a bissextile year. To maintain the calendar year in line with the astronomical year or seasonal year, the 366th day (or 13th month) is added. Calendars with a fixed number of days per year will inevitably drift over time with respect to the event that the year is designed to chronicle, such as seasons, since astronomical events and seasons do not recur in a complete number of days. A civilization's dating system and the physical characteristics of some years might drift apart by "intercalating" (adding) a leap day or leap month.

Astronomical years have a duration of somewhat less than 365 1 /4 days. In the ancient Julian calendar, February is extended to 29 days instead of the usual 28, and there are three common years of 365 days, followed by a leap year of 366 days. The most used civil calendar in the world, the Gregorian calendar, further corrects for the tiny inaccuracy in the Julian method. There are 366 days in a leap year as opposed to 365. Every year that is a multiple of four has an additional leap day (with the exception of years that are equally divisible by 100 but not by 400).

A fixed date in the Gregorian calendar advances one day of the week from one year to the next; however, the day of the week in the 12 months that follow the leap day (from 1 March through 28 February of the following year) will advance two days due to the extra day, thus leaping over one day in the week. This is most likely where the term "leap year" originates.[2][3] In 2020, 2021, 2022, 2023, and 2024, Christmas Day (December 25) fell on a Friday. However, in 2024, it will "leap" over Tuesday and fall on a Wednesday.

Coordinated Universal Time (UTC) is periodically updated to reflect the addition of a leap second to determine the duration of a day.

Although the majority of people would generally agree that there are exactly 365 days in a year, it isn't quite accurate. In actuality, the earth's orbit around the sun takes precisely 365 and one-fourth days. This indicates that a "correction day," or an extra day added to account for the extra one-fourth of a day, must be held every four years in order for the years to be completely accurate and precise.

The Roman calendar had only 355 days, which made its history quite convoluted. Caesar's calendar reform resulted in the addition of a "leap day," although it remained somewhat ambiguous. Pope Gregory XIII instituted the Gregorian calendar, which started in the late 1500s.

Nevertheless, Leap Year Day represents more than just an extra day in February. Actually, the day is marked by a number of fascinating traditions and customs in addition to a few superstitions, such as those involving ill luck. For example, there is a myth in Greece that marriages consummated in a leap year will not work out well.

For example, Irish folklore is the source of the tradition that a woman can propose to a man on Leap Year Day. In Scotland, it was customary for ladies who planned to pop the question to wear a crimson petticoat that day. Additionally, there might have been a fine for a male on Leap Year Day who turned down a woman's proposal.

When a year is incorrectly recognized as a leap year or when logic that accepts or manipulates dates handles February 29 incorrectly, leap years can cause a computer issue known as the leap year bug.