The Mass is the complex of prayers and ceremonies that make up the service of the Eucharist in the Latin rites. As in the case of all liturgical terms the name is less old than the thing.
From the time of the first preaching of the Christian Faith in the West, as everywhere, the Holy Eucharist was celebrated as Christ had instituted it at the Last Supper, according to His command, in memory of Him.
But it was not till long afterwards that the late-Latin name Missa, used at first for dismissal, became the technical and almost exclusive name for the entire service.
The Mass follows a “fundamental structure which has been preserved throughout the centuries down to our own day” (Catechism of the Catholic Church, no. 1346).
Though the Mass is one united act of worship, it consists of many parts, each with its own purpose and meaning. These many parts are found in four major divisions within the celebration, which are: the Introductory Rites; the Liturgy of the Word; the Liturgy of the Eucharist; and the Concluding Rites. (9:44)