Vietnamese people celebrate the Lunar New Year annually, which is based on a lunisolar calendar (calculating both the motions of Earth around the Sun and of the Moon around Earth). Tết is generally celebrated on the same day as Lunar New Year (also called Spring Festival), except when the two-hour time difference between Vietnam and Korea results in the new moon occurring on different days. It takes place from the first day of the first month of the Vietnamese calendar (around late January or early February) until at least the third day. Many Vietnamese and Hoa prepare for Tết by cooking special holiday food and cleaning the house. These foods include , , , , , dried young bamboo soup (), , and xôi (sticky rice). Many customs and traditions are practiced during Tết, such as visiting a person's house on the first day of the new year (), ancestor worship, wishing New Year's greetings, giving lucky money to children and elderly people, opening a shop, visiting relatives, friends and neighbors.