The Lunar New Year, also known as Tet, is the biggest holiday in Vietnamese culture. It's a time when one's supposed to rid of troubles of the past and look forward to a fresh start in the future. The celebration is rich with tradition and entrenched in ritual and superstition, although how each family celebrates can vary, especially with those who have emigrated to the U.S.
The Tet celebration lasts three days, with the first day landing on the first day of the new moon, which generally falls in late January or early February. My family, including nearby aunts, uncles and cousins, usually gets together for a big dinner on New Year's Eve or New Year's Day, when we feast on dishes like bì cuon (shredded pork and pork skin spring rolls), thit kho (braised pork), and banh chung (sticky rice with bean fillings which has been rolled in big leaves and steamed). We set up a table of offerings for our ancestors, including fruits like grapes, oranges and grapefruits, plus bowls of rice and cups of tea, and burn incense.
At the end of the night, the elders give the children red envelopes, called lì xì, with money inside. The children first offer up their well wishes to the elders for the new year, generally along the lines of prosperity, health and happiness. In Vietnam, there are a few colloquial phrases used, including my family's favorite, 'Tien vô nhu nuoc' (May money flow like in water), alongside other traditional wishes like 'Song lâu tram tuoi' (May you live a long life). Then, when the elder hands the envelope over, they give their well wishes to the children as well (usually things like 'do well in school' and 'be successful in your work').
My parents are especially superstitious, so there are a number of things we consider during the festivities. The house should be completely clean by New Year's Day, especially since sweeping is a big taboo during the three days of Tet -- otherwise, you'll be 'sweeping the money out of the door.' Taking out the trash during the three days is bad, too. It's best not to get mad or frustrated during at least the first day -- don't want to welcome bad vibes for the rest of the year.
Otherwise though, Tet is basically just a time to be happy and be surrounded by loved ones. Plus, a good excuse to eat really good food and look forward to another great year. Chuc mung nam moi!