What Is a Leap Year?

A leap year is a calendar year that contains an additional day, February 29th, to keep our calendar in alignment with the Earth's revolutions around the Sun.

Quick Answer

A leap year has 366 days instead of the usual 365. That extra day is February 29th. It happens every four years to keep our calendar in sync with the Earth's orbit around the sun, which actually takes about 365 and a quarter days.

A leap year occurs every 4 years, except for years divisible by 100 but not by 400. This extra day, February 29th, is added to align the calendar year with the astronomical year.