The word "liturgy" originally meant a "public work" or a "service in the name of/on behalf of the people." In Christian tradition it means the participation of the People of God in "the work of God." Through the liturgy, Christ, our redeemer and high priest, continues the work of our redemption in, with, and through his Church. -Catechism of the Catholic Church 1069
The whole liturgical life of the Church revolves around the Eucharistic sacrifice and the sacraments. There are seven sacraments in the Church: Baptism, Confirmation or Chrismation, Eucharist, Penance, Anointing of the Sick, Holy Orders, and Matrimony.
Sacraments are "powers that comes forth" from the Body of Christ, which is ever-living and life-giving. They are actions of the Holy Spirit at work in his Body, the Church. They are "the masterworks of God" in the new and everlasting covenant.
Catechism of the Catholic Church 1113 and 1116