The Eucharist ( /ˈjuːkərɪst/), also called Holy Communion, the Sacrament of the Altar, the Blessed Sacrament, the Lord's Supper, and other names, is a Christian sacrament or ordinance. It is reenacted in accordance with Jesus' instruction at the Last Supper as recorded in several books of the New Testament, that his followers do in remembrance of Him as when he gave his disciples bread, saying, "This is my body", and gave them wine, saying: "This is my blood."
There are different interpretations of the significance of the Eucharist, but according to the Encyclopædia Britannica "there is more of a consensus among Christians about the meaning of the Eucharist than would appear from the confessional debates over the sacramental presence, the effects of the Eucharist, and the proper auspices under which it may be celebrated."
The word Eucharist may refer not only to the rite but also to the consecrated bread (leavened or unleavened) and wine (or unfermented grape juice in some Protestant denominations, water in the LDS Church's sacrament), used in the rite. In this sense, communicants (that is, those who partake of the communion elements) may speak of "receiving the Eucharist", as well as "celebrating the Eucharist".
Read more about Eucharist: Names, Eucharistic Theology, Open and Closed Communion