Lunar New Year
The biggest holiday of Vietnamese is Lunar New Year. Most of Vietnamese want to come to hometown where they were borned to visit related people. Especially, Lunar Year is also called Tet has a traditional activity is lixi to Olders and Children. 
Most ancient societies used to celebrate New Year at different times from what we now do in the west. Many cultures celebrated New Year on March 21st and the official beginning of spring. The fact we celebrate 01/01 each year was implimented by the Romans as a way to divert the masses away from the true power of Astrology and how it worked in peoples everyday life.
Exactly! Each cultures have different New Year Holiday. Vietnamese celebrated West New Year in Jan 1st, and now we have Traditional New Year, it has been established for more than thousand years and be maitanded continuously. Hope the lucky to every in the world.