From YOUCAT, fact 167:
167: What is liturgy?
LITURGY is the official divine worship of the CHURCH.
A LITURGY is not an event that depends on good ideas and great songs. No one makes or invents a liturgy. It is something living that grew over millennia of faith. A Mass is a holy, venerable action. Liturgy becomes exciting when one senses that God himself is present under its sacred signs and its precious, often ancient prayers.