What is a sacrament?
The whole liturgical life of the Church revolves around the sacraments, especially the eucharist (communion).
A sacrament is a rite or ceremony of the Church which bestows special inward grace on the recipient. The sacrament is the outward and visible sign of that inward, spiritual grace.
The seven sacraments are: Baptism, Confirmation, Eucharist, Penance (confession), Anointing of the Sick, Holy Orders (ordination) and Matrimony (marriage).