Hát thờ: singing to sacrifice to patron; to tutelary god in villages’ communal houses; and to deities in temples.

Hát chơi: singing in private houses (congratulation on the occasion of assuming mandarin, giving birth to a son, inaugurating a new house, and wedding), and singing for entertainment in residence builings.

Hát thi: singing to compete in villages (contests between music schools in order to select persons who sing well).

On special occasions: sing to congratulate King on his longevity, singing in rituals to receive foreign emissaries.

As an artistic subject which has old age, uniqueness and special meaning in singing and music treasure of Vietnamese people, Ca trù, for many centuries, has undergone a long process of  development and has penetrated into most of cultural and spiritual fields of Vietnamese people such as feasts and festivals, custom, religion, diplomacy, literature, music, though, and life philosophy.