The word "liturgy" originally meant a "public work" or a "service in the name of/on behalf of the people." In Christian tradtion it means the participation of the People of God in "the work of God."Jn 17:4 CCC#1069
Liturgical services are not private but are celebrations of the Church, which brings unity, the whole Body of the Church. In assisting in the liturgies, there are ministires for the faithful to assist the ordained ministers with functions such as Servers, Readers, EMHC, Choir, Greeters and Ushers.