Original: The Roman Catholic Church still officially considers Gregorian chant the music most suitable for worship in the Roman Rite, and should be given the "pride of place" in all Masses in the Roman Rite (see GIRM, P41).
Simplified: In Roman Catholic churches, prayers and songs follow an order called the "Roman Rite." Gregorian chant is the music used in the Mass and the Office of the Roman Rite.