The difference between leap year and ordinary year:
1. Different meanings. In case of a whole hundred years, it is a leap year to be divided by 400, otherwise it is a normal year; In case of a non whole century, as long as it is divided by 4, it is a leap year, and it cannot be divided by 4 into a normal year.
2. The number of days is different. There are 29 days in February of leap year and 28 days in February of normal year.
Leap year is set up to make up for the time difference between the annual days and the actual revolution cycle of the earth caused by man-made calendar. The year making up the time difference is leap year.
The leap year has 29 days in February and 366 days in the whole year. It is divided into ordinary leap year and century leap year. Ordinary leap year means that the Gregorian calendar year is a multiple of 4, not a multiple of 100, and the century leap year must be a multiple of 400.
A weekday is a year in which there is no leap day in the Gregorian calendar or no leap month in the lunar calendar. The number of A.D. years can be divided by 4 as leap years, but the number of years of a hundred (both the number of digits and the number of tens are 0) must be divisible by 400 as leap years (for example, 1900 is not a leap year), and others are normal years. The year with leap month in the lunar calendar is called leap year. The lunar calendar adopts the method of 19 years plus 7 leap months, namely "19 years and 7 leap method", that is, there are 7 leap years in the 19 years of the lunar calendar.