Chinese calendar, a lunisolar calendar, is formed on the movement of the moon and the sun. It is also called the Lunar calendar, Yin calendar, Xia calendar or the old Chinese calendar. Each Chinese calendar year has a zodiac sign, 12 or 13 months and each month has 29 or 30 days. If there are 12 months, there will be 354 or 355 days in a year; if 13 months, there will be 383 or 384 days. Although China has adopted the Gregorian calendar for official and business occasions, the traditional Chinese calendar is widely used to define 24 solar terms, traditional holidays and helps to choose a lucky day before important activities such as wedding, moving into a new house.