The Roman Rite has been adapted over the centuries and the history of its Eucharistic liturgy can be divided into three stages: the Pre-Tridentine Mass, Tridentine Mass and Mass of Paul VI. The Mass of Paul VI is the current form of the Mass in the Catholic Church, first promulgated in the 1969 edition of the Roman Missal. It is considered the ordinary form of the mass, intended for most contexts. The Tridentine Mass, as promulgated in the 1962 Roman Missal, may be used as an extraordinary form of the Roman Rite, according to norms set in the 2007 papal document Summorum Pontificum.
The Roman Rite is noted for its sobriety of expression. In its Tridentine form, it was noted also for its formality: the Tridentine Missal minutely prescribed every movement, to the extent of laying down that the priest should put his right arm into the right sleeve of the alb before putting his left arm into the left sleeve (Ritus servandus in celebratione Missae, I, 3). Concentration on the exact moment of change of the bread and wine into the Body and Blood of Christ has led, in the Roman Rite, to the consecrated Host and the chalice being shown to the people immediately after the Words of Institution. If, as was once most common, the priest offers Mass while facing ad apsidem (towards the apse), ad orientem (towards the east) if the apse is at the east end of the church, he shows them to the people, who are behind him, by elevating them above his head. As each is shown, a bell (once called "the sacring bell") is rung and, if incense is used, the host and chalice are incensed (General Instruction of the Roman Missal, 100). Sometimes the external bells of the church are rung as well. Other characteristics that distinguish the Roman Rite from the rites of the Eastern Catholic Churches are frequent genuflections, kneeling for long periods, and keeping both hands joined together.
In his 1912 book on the Roman Mass, Adrian Fortescue wrote: "Essentially the Missal of Pius V is the Gregorian Sacramentary; that again is formed from the Gelasian book, which depends on the Leonine collection. We find the prayers of our Canon in the treatise de Sacramentis and allusions to it in the 4th century. So our Mass goes back, without essential change, to the age when it first developed out of the oldest liturgy of all. It is still redolent of that liturgy, of the days when Caesar ruled the world and thought he could stamp out the faith of Christ, when our fathers met together before dawn and sang a hymn to Christ as to a God. The final result of our inquiry is that, in spite of unsolved problems, in spite of later changes, there is not in Christendom another rite so venerable as ours." In a footnote he added: "The prejudice that imagines that everything Eastern must be old is a mistake. Eastern rites have been modified later too; some of them quite late. No Eastern Rite now used is as archaic as the Roman Mass."
In the same book, Fortescue acknowledged that the Roman Rite underwent profound changes in the course of its development. His ideas are summarized in the article on the "Liturgy of the Mass" that he wrote for the Catholic Encyclopedia (published between 1907 and 1914) in which he pointed out that the earliest form of the Roman Mass, as witnessed in Justin Martyr's 2nd-century account, is of Eastern type, while the Leonine and Gelasian Sacramentaries, of about the 6th century, "show us what is practically our present Roman Mass". In the interval, there was what Fortescue called "a radical change". He quoted the theory of A. Baumstark that the Hanc Igitur, Quam oblationem, Supra quæ and Supplices, and the list of saints in the Nobis quoque were added to the Roman Canon of the Mass under "a mixed influence of Antioch and Alexandria", and that "St. Leo I began to make these changes; Gregory I finished the process and finally recast the Canon in the form it still has."
Fortescue himself concluded: