Leap day

A leap year is a calendar year that contains an additional day added to keep the calendar year synchronized with the astronomical year or seasonal year.

February 29 also known as leap day or leap year day, is a date added to most years that are divisible by 4, such as 2016, 2020, and 2024. A leap day is added in various solar calendars (calendars based on the Earth’s revolution around the Sun), including the Gregorian calendar standard in most of the world.

These extra days occur in each year which is a multiple of 4 (except for years evenly divisible by 100, which do not leap years unless evenly divisible by 400)