The prayers that comprise the Rosary are arranged in sets of ten Hail Marys, called decades. Each decade is preceded by one Lord's Prayer and followed by one Glory Be. During recitation of each set, thought is given to one of the Mysteries of the Rosary, which recall events in the lives of Jesus and Mary. Five decades are recited per rosary. Other prayers are sometimes added before or after each decade. Rosary beads are an aid towards saying these prayers in the proper sequence.
A standard 15 Mysteries of the Rosary, based on the long-standing custom, was established by Pope Pius V during the 16th century, grouping the mysteries in three sets: the Joyful Mysteries, the Sorrowful Mysteries, and the Glorious Mysteries. During 2002 Pope John Paul II said that it is fitting that a new set of five be added, termed the Luminous Mysteries, bringing the total number of mysteries to 20. These mysteries had been used by Holy Cross father Patrick Peyton during the 20th century. The Glorious mysteries are said on Sunday and Wednesday, the Joyful on Monday and Saturday, the Sorrowful on Tuesday and Friday, and the Luminous Mysteries are said on Thursday. Usually five decades are recited in a session.
For more than four centuries, the rosary has been promoted by several popes as part of the veneration of Mary in Roman Catholicism, and consisting essentially in meditation on the life of Christ. The rosary also represents the Roman Catholic emphasis on "participation in the life of Mary, whose focus was Christ", and the Mariological theme "to Christ through Mary."
During the 16th century, Pope Pius V associated the rosary with the General Roman Calendar by instituting the Feast of Our Lady of Victory (later changed to Our Lady of the Rosary), which is celebrated on 7 October.
Pope Leo XIII, known as "The Rosary Pope," issued twelve encyclicals and five apostolic letters concerning the rosary and added the invocation Queen of the most Holy Rosary to the Litany of Loreto. Pope Pius XII and his successors actively promoted veneration of the Virgin in Lourdes and Fatima, which is credited with a new resurgence of the rosary within the Catholic Church. Pope John Paul II issued the Apostolic Letter Rosarium Virginis Mariae which emphasized the Christocentric nature of the Rosary as a meditation on the life of Christ.