The lunar calendar is China's traditional calendar, also called the Yin calendar, Hua calendar, summer calendar, Han calendar, Zhong calendar and other names. According to the lunar calendar, the change period of lunar phases is the length of the synodic moon, with the composition of "twenty-four solar terms" in the dry-branch calendar. The solar tropical year is referred to as the length of the year.Besides, the lunar calendar is based on the Yin calendar (summer calendar), which combines elements of the solar calendar. So technically speaking, our lunar calendar should not be called the lunar calendar, but the yin-yang calendar.
The lunar year is divided into ordinary years and leap years. The ordinary year is twelve months; In a leap year there are thirteen months. The months are divided into the big months and the small months, the big months 30 days, the small months 29 days, its average calendar month is equal to a full moon. Whether big or small is determined by calculation.
The lunar calendar takes the relationship between the sun, moon and earth into account and does not consider the earth's orbit around the sun. Therefore, season changes on the lunar calendar does not have fixed time, can not reflect the seasons. The number of days in the lunar year is sometimes one month different from that in the solar year. In order to coordinate the number of days between the synodic month and the tropic year, the number of days of the lunar month was adjusted to the number of days of the tropic year in the solar calendar through the "placement leap method".
From the power of ancient era to the late Qing dynasty to enable western (Gregorian calendar), repeatedly revised calendar history, produced more than 102 units Chinese calendar in total, which has exerted a significant influence on Chinese culture and civilization. Although some calendars were even not formally used, they still contributed to preserving one's health, medical, academic thought, astronomy and mathematics.
After the foundation of the republic of China, the western calendar was adopted and the western calendar and the republican calendar were adopted to count the years, which leads to the traditional Chinese calendar’s abolishment. When the People's Republic of China was founded in 1949, it continued to use the western calendar to mark the year in the Christian era. However, it retained the use of the traditional Chinese calendar, the lunar calendar, and promulgated the national standard "the compilation and promulgation of the lunar calendar" in 2017. The current lunar calendar is calculated by the Purple Mountain Observatory of the Chinese Academy of Sciences and is a part of the official almanac, “the Chinese astronomical almanac”.