A sacrament is a Christian rite that mediates divine grace—a holy mystery. The root meaning of the Latin word sacramentum is "making sacred". One example of its use was as the term for the oath of dedication taken by Roman soldiers; but the ecclesiastical use of the word is derived from the root meaning of the word and not from that particular example.

The Roman Catholic Church, Eastern Orthodox (Byzantine) Christians, the Oriental Orthodox, Assyrian Christians (or the Church of the East) hold that sacraments are not mere symbols, but rather, "signs or symbols which effect what they signify", that is, the sacraments in and of themselves, rightly administered, are used by God as a means to communicate grace (Himself) to faithful recipients. These Churches all accept that there are seven sacraments.

These are: Baptism, Confirmation, the Mass or Eucharist (including the reception of Holy Communion), The Sacrament of Order (Ordination), Reconciliation of a Penitent (confession), The Sacrament of the Sick (Anointing of the Sick), and Matrimony. Most of these have been celebrated continually since their institution by Jesus Christ.

In the Western Catholic tradition, a Sacrament is often and accurately defined as "an outward, visible sign that conveys an inward, spiritual grace".