Yuandan is the first day of the lunar calendar. It is the day when the earth has circled the sun for one round and is beginning another circling. It represents a new beginning when people send off the old days and welcome the new ones. As the first day of the year, Yuandan has been considered to be the most important festival since the ancient times.
Kaisui(beginning of the year): According to the Chinese traditional custom, starting from haishi(9p.m. to 11p.m.)of the last evening of the twelfth lunar month, each family must prepare offering s to deities at the altar. At the same time, they too prepare food for the New Year day: The whole family will then stay awake together to attend to the year(called shou sui).
After haishi, zishi(11p.m. to 1a.m.)will come, and this is the arrival of New Year(Yuandan). At this moment, people begin the celebration with fireworks. Vegetarian and sweet foods will then be placed are the altar for offerings, and incense be burned to welcome the deities. In the ancient times, it was believed that haishi connected the two years and thus was called kaisui