a leap year的意思|示意

Leap year, also known as intercalary year or bissextile year, is a calendar year containing an extra day (or, in the case of lunisolar calendars, a month) added to keep the calendar year synchronized with the astronomical or seasonal year. Leap year occurs every four years, when the year can be evenly divided by 4. In other words, the leap year happens once every 4 years.

A leap year has 366 days instead of 365. The extra day is called a leap day and is added to the month of February. In a leap year, February has 29 days instead of the usual 28 days. In other words, the leap year happens once every 4 years, and a leap day is added in February.

In the Gregorian calendar (the most widely used calendar system today), three conditions must be met for a year to be a leap year. First, the year must be evenly divisible by 4. Second, if the year can be evenly divided by 100, it is not a leap year, unless it can also be evenly divided by 400. That means, for example, that the year 2000 was a leap year, because it was divisible by both 100 and 400.

In certain countries like Japan, however, the leap year is calculated according to the traditional Japanese calendar (Kyuureki), which is based on the Chinese calendar. According to the traditional Japanese calendar, a leap year occurs every 3 years (instead of every 4 years) when the month of February has 30 days.

Leap years have played a major role in history, helping to keep calendars in sync with the sun and moon. Today, they continue to play an important role in keeping our calendars organized.