Vietnam’s traditional lunar New Year festival (Tet in Vietnamese) started on February 6 (December 23 of the lunar calendar) when people worshiped “The Kitchen God” and will last until the main celebration days of February 13-18 this year (December 30 – January 5 of the lunar calendar).
Tet can be divided into three periods, known as Tat nien (Before New Year's Eve), Giao Thua (New Year's Eve), and Tan Nien (the New Year).
The “Before New Year's Eve” period begins one or two weeks before the actual celebration. The general atmosphere leading up to Tet is in the bustle of shopping, decorating the home, cooking traditional Tet food and waiting for relatives to return home.
The first day of Tet is reserved for the nuclear family. Children receive a red envelope containing money from their elders. Usually, children wear their new clothes and give their elders the traditional Tet greetings before receiving the money. Since the Vietnamese believe that the first visitor a family receives in the year determines their fortune for the entire year, people never enter any house on the first day without being invited first. According to Vietnamese tradition, if good things come to the family on the first day of the lunar New Year, the entire following year will also be full of blessings. Usually, a person of good temper, morality and success will be the lucky sign for the host family and be invited first into the house.
During the subsequent days, people visit relatives and friends. Traditionally, but not strictly, the second day of Tet is usually reserved for friends, while the third day is for teachers.
(Source: VietNamplus)