The word liturgy, derived from a term in ancient Greek (λειτουργία), literally means "work of the people.” It best describes the effort of the Church, with the grace of God, to worship Him in a ritual that aims to bring the People of God into direct union with the divine. Although various liturgical rituals can be found in the Church's efforts to worship God, when we simply speak of "Liturgy,” it is often in reference to what we now commonly call the Mass (from the Latin word "Missa" meaning "going forth") or the Eucharist (from the Greek word meaning "Thanksgiving").

Although its ritual form is often articulated through rich and cultural language, the Liturgy of the Mass is not man-made. Instead, it stems from Christ's very own ritual in the context of His Last Supper with His chosen disciples, the manner and the words He used when He took bread and wine saying, "This is my Body" and "This is my Blood" and then telling His disciples to “Do this in memory of Me.” The ritual Our Lord expressed the night before His sacrificial death, as recounted in the four accounts of the Last Supper, in Matthew, Mark, Luke, and 1 Corinthians, has provided a template form from which the liturgy and ritual of the Mass have developed throughout the ages.

The Second Vatican Council (1962 - 1965) re-echoed the timeless assertion that the Mass is the summit towards which all the activity of the Church is directed and the fountain from which all graces flows. Recognizing the Mass as a joining of the ritual of our earthly worship to that of the angels and saints in their praise and worship before the divine presence of the "Lamb that was sacrificed but now lives,” some have described the Liturgy of the Mass as the “most beautiful thing this side of Heaven.”