Tết Nguyên Đán, more commonly known by its shortened name Tết, is the most important and popular holiday and festival in Vietnam. It is the Vietnamese New Year derived from the Chinese New Year based on the Lunar calendar, a lunisolar calendar. The name Tết Nguyên Đán is Sino-Vietnamese for Feast of the First Morning, derived from the Hán nôm characters 節元旦.