Liturgy comes from the Greek leitourgia which means "the work of the people."
Perhaps this is more easily understood as communal worship such as Masses (the Divine Liturgy), Communion Services, Reconciliation Services, Liturgies of the Word and Liturgy of the Hours. Christ is always present in his church, especially in its liturgical celebrations. In the earthly liturgy, we take part in a foretaste of the heavenly liturgy celebrated in the holy city of Jerusalem toward which we journey as pilgrims. Along the way we engage in the work of sharing with others the good tidings of salvation, modeling faith and penance, witnessing to the power and grace of the sacraments, and inviting others to join us in work of charity, worship and discipleship. - The Liturgy Documents, Chapter 1: Nature of the Liturgy and Its Importance in the Church's Life, loosely based on paragraphs #7, #8 and #9.