The Mass of Paul VI, also known as the Ordinary Form or Novus Ordo, is the most commonly used liturgy in the Catholic Church. It was promulgated by Pope Paul VI in 1969 and its liturgical books were published in 1970; those books were then revised in 1975, they were revised again by Pope John Paul II in 2000, and a third revision was published in 2002.

Catholic liturgy means the whole complex of official liturgical worship, including all the rites, ceremonies, prayers, and sacraments of the Church, as opposed to private devotions. In this sense the arrangement of all these services in certain set forms is meant. Liturgy encompasses the entire service: prayer, reading and proclamation, singing, gestures, movement and vestments, liturgical colours, symbols and symbolic actions, the administration of sacraments and sacramentals.