§1. The eucharistic celebration is the action of Christ himself and the Church. In it, Christ the Lord, through the ministry of the priest, offers himself, substantially present under the species of bread and wine, to God the Father and gives himself as spiritual food to the faithful united with his offering.
§2. In the eucharistic gathering the people of God are called together with the bishop or, under his authority, a presbyter presiding and acting in the person of Christ. All the faithful who are present, whether clerics or laity, unite together by participating in their own way according to the diversity of orders and liturgical functions.
§3. The eucharistic celebration is to be organized in such a way that all those participating receive from it the many fruits for which Christ the Lord instituted the eucharistic sacrifice.
Source: Code of Canon Law (Vatican.va)