Ancestor worship is Vietnam's most widespread folk practice, coexisting alongside various religions (Buddhism, Catholicism, Caodaism, and others). It isn't strictly a "religion" with its own doctrine, but a folk belief system, practices centered on remembering and honoring deceased family members.
Most Vietnamese households, regardless of religion, keep a family altar in a place of honor (often the central room, facing the main door), typically holding an incense bowl, ancestor photos or memorial tablets, candles, and fresh fruit and flowers refreshed on holidays, Tet, and the new/full moon days each lunar month.
The death anniversary is an important yearly occasion for descendants to gather and prepare an offering meal in remembrance. The first anniversary and the third-year anniversary (marking the traditional end of mourning) are typically observed more elaborately than later ones.
Beyond individual death anniversaries, shared ancestor-related observances through the year include the first full moon of the lunar year, the Thanh Minh tomb-sweeping festival, the seventh lunar month full moon (Vu Lan, a festival of filial piety), and the year-end and New Year's Eve offerings during Tet, all occasions to symbolically invite ancestors to "return" and join the living family.
Beyond its spiritual dimension, ancestor worship reflects the moral principle of "remembering the source of the water you drink", valuing gratitude and the bond between generations. It's considered one of the core cultural values sustaining family cohesion across generations of Vietnamese people.
