Because leap years occur every four years, only leap years have February 29. Leap year is a term in the calendar, which is divided into ordinary leap year and century leap year.

LeapYear was established to make up for the time difference between the number of days in a year caused by man-made calendar regulations and the actual period of revolution of the earth. The year to make up for the time difference is leap year. The leap year has 366 days (respectively 1 day, 29 days, 3 1 day, 30 days, 3 1 day, 30 days, 3 1 day, 3 1 day.