What is the average number of days in a leap year?

In a leap year, an extra day is added to the standard 365 days of a typical year, which brings the total to 366 days. This additional day, February 29, occurs every four years to help synchronize the calendar year with the astronomical year, as the Earth takes approximately 365.25 days to complete one orbit around the Sun. Therefore, the average number of days in a leap year is correctly identified as 366 days. This adjustment ensures that the seasons remain aligned with the calendar.