The Zoroastrian liturgical text containing hymns and rituals is the Yasna.
Yasna names both a major text within the Avesta and the central Zoroastrian act of worship based on reciting that text. The word comes from an Avestan term meaning worship, sacrifice, or oblation. A complete Yasna service combines priestly recitation with ritual actions, including preparation and offering of haoma and an offering to the waters.
The Yasna contains 72 chapters assembled over different periods. Its central and oldest sections include the Gathas, the sacred hymns traditionally attributed to Zarathustra. Other chapters consist of invocations, praises, liturgical instructions, and prayers addressed to Ahura Mazda and other divine beings. A normally performed service can take about two hours for an experienced priest.
Yasna is often confused with the Gathas because the Gathas are embedded within it. It is also distinct from the Yashts, which are individual hymns honoring particular divinities, and from the Visperad and Vendidad, texts that can extend or accompany certain ceremonies. The Yasna is therefore both a scripture collection and the ritual framework in which much of that scripture is performed.