A leap year consists of 366 days.
This additional day is added to the calendar in February, giving it 29 days instead of the usual 28. Leap years occur every four years to help synchronize the calendar year with the astronomical year, or the time it takes the Earth to complete its orbit around the Sun, which is approximately 365.25 days. By adding an extra day every four years, we can keep our calendars aligned with the seasons.