Leap year is an extra day added to the calendar every four years to keep the calendar in sync with the seasons. This extra day is known as February 29th and occurs every four years, making the year 366 days long rather than the typical 365. This extra day is necessary to keep the calendar in line with the solar year, in which a full orbit around the sun takes 365.24 days to complete. A leap year occurs in any year evenly divisible by 4, such as 2020, 2024, and 2028.
