How many days are there in a leap year?

A leap year has 366 days. This is because a leap year includes an extra day, February 29th, to help synchronize the calendar year with the astronomical year. Normally, a standard year has 365 days, but every four years, an additional day is added to account for the fact that it actually takes about 365.25 days for the Earth to complete its orbit around the Sun. This adjustment prevents the calendar from drifting out of sync with the seasons. Hence, in a leap year, the total is 366 days.