Hát chầu văn, or in secular form hát văn, is a traditional folk art of northern Vietnam which combines trance singing and dancing. Its music and poetry are combined with a variety of instruments, rhythms, pauses, and tempos. Hát chầu văn originated in the 16th century and spread quickly. The main musical instrument used in hat van performance is the dan nguyet or moon-shaped lute. The genre is famous for its use in rituals for deity mediumship. Chau Van serves two purposes: to help hypnotize the medium for reception of the deities and to accompany the medium's actions with appropriate music.
The singing and dance in non-religious form is hát văn ("sung literature") without the word chầu ("supplication").
^Pattana Kitiarsa, Religious commodifications in Asia: marketing gods, 2008, p. 161. "..master (thầy cúng) reading the questions, by the attendants of the spirit medium during the ritual, and by the musicians (chầu văn) accompanying, explaining and commenting on the ritual. The ritual usually takes from a couple of hours, ..."
^Endres, Andrea Lauser, Engaging the Spirit World: Popular Beliefs and Practices in Modern Southeast Asia. Edited by Kirsten W. Endres and Andrea Lauser. 2012, p. 93. "Images from this past are enacted during spirit possession rituals, such as Mrs Bình's, by dressing in the appropriate ritual costumes and in the songs of the chầu văn musicians."
^Taylor, Philip, Modernity and Re-Enchantment: Religion in Post-Revolutionary Vietnam 2007, p. 197. "During the Lady spirits' manifestations, Nguyệt's husband suggests flowing arm and hand movements and gracefully flexes his fingers in tune with the rhythm of the chầu văn music that accompanies the ritual, while the other ritual ..."