What is the of Eucharist?

The Eucharist is "the source and summit of the Christian life."  (Lumen Gentium, paragraph 11) Put simply, the Eucharist is the real presence of Christ, under the appearance of bread and wine. Catholics believe that Christ, through the priest (who acts in the person of Christ), makes Himself really present.   In fact, although the appearance of the bread and wine doesn't change, Catholics believe they undergo a change of substance (transubstantiation).  The bread and wine become the real presence of Christ.  The celebration of the sacrament of the Eucharist is called Mass.

The celebration of the Eucharist dates back to the earliest days of the Church.  Catholics believe Christ instituted this sacrament at His Last Supper, when he said to the disciples, "This is my body, take and eat; This is my blood, take and drink."  Indeed so significant is this event it is recounted in the gospels of Matthew, Mark and Luke. And in the gospel of John, the words of Christ are clear:  The eating of the body of Christ and the drinking of the blood of Christ are intimately connected to Christ's gift of salvation.

The Catechism reminds us that in the tradition of the Church, the Eucharist is referred to by a number of titles.  The word Eucharist comes from two Greek words meaning "thanksgiving".  Also, these two Greek words recall the "Jewish blessings that proclaim -- especially during a meal -- God's works:  creation, redemption, and sanctification."  (CCC, paragraph 1328)

It is referred to as The Lord's Supper, as recounted in the gospels and Paul's First Letter to the Corinthians, "because of its connection with the supper which the Lord took with his disciples on the eve of his Passion and because it anticipates the wedding feast of the Lamb in the heavenly Jerusalem."  (CCC, paragraph 1329).

"The Breaking of Bread, because Jesus used this rite, part of a Jewish meal, when as master of the table he blessed and distributed the bread, above all at the Last Supper.  It is by this action his disciples will recognize him after his Resurrection, and it is this expression that the first Christians will use to designate their Eucharistic assemblies."   (CCC, paragraph 1329)

"The Eucharistic Assembly (synaxis), because the Eucharist is celebrated amid the assembly of the faithful, the visible expression of the Church."  (CCC, paragraph 1329)

"The memorial of the Lord's Passion and Resurrection.

The Holy Sacrifice, because it makes present the one sacrifice of Christ our Savior and includes thte Church's offering.  The terms 'holy sacrifice of the Mass', 'sacrifice of praise,' 'spiritual sacrifice', 'pure and holy sacrifice' are also used, since it completes and surpasses all the sacrifices of the Old Covenant.

The Holy and Divine Liturgy, because the Church's whole liturgy finds its center and most intense expression in the celebration of this sacrament; in the same sense we also call its celebration the Sacred Mysteries.   We speak of the Most Blessed Sacrament because it is the Sacrament of sacraments. (CCC, paragraph1330)

Only baptized Catholics receive the Eucharist.   Generally, Catholics make their First Communion (the celebration of the first reception of the Eucharist) at the age of 7 or 8, but  many do make their First Communion as teenagers or adults.

With the exception of Eastern Churches most other Christian churches do not share the belief of Catholics that the Eucharist is the real presence of Christ.  Because the Eucharist is the real presence of Christ for us, which represents our unity of faith in Christ, Catholics reserve reception of the Eucharist to those baptized Catholics who share completely the unity of the faith.   Admitting only baptized believers to the Eucharist was the practice of the early Church.