清明节是中国最重要的祭祀节日之一， dating back to the Zhou Dynasty over 2,500 years ago. It is a traditional Chinese holiday where people visit their ancestors' tombs to honor them and clean their graves. The festival is also known as 清明节, treaded青岛分公司方寸国学馆, and is celebrated on the 15th day of the first month in the lunar calendar.