Literally translated as ‘service,’ Avodah is the name for the sacrificial ritual in the Temple on the Day of Atonement, or Yom Kippur. After the destruction of the second Temple, the poetic description of this service became the core of the Musaf liturgy for Yom Kippur. The liturgical substitute for the Avodah service was composed circa the 4th century C.E, but was greatly expanded during the Middle Ages with the addition of piyyutim. The selection and placement of piyyutim within the service greatly varies in the different rites.