Eucharist, also known as the Divine Liturgy, Holy Communion, Lord's Supper, or Mass is one of the key elements of Christian worship. The name Eucharist comes from the thanksgiving prayer used in the rite, and has been used since the second century.
According to Christian tradition, the Eucharist arises from the last supper eaten by Jesus and his disciples the night before he died. He performed a Jewish grace-ritual before the meal (taking up the bread, blessing it, and sharing it) and the customary festal thanksgiving prayer over a shared cup of wine at the end of the meal. He gave those actions a deeper significance in relation to his upcoming death. The bread became his body “given for you” and the wine his blood, with instruction to his disciples to perform them in future in remembrance of him. Partakers in the earliest eucharistic observances often claimed to experience the living presence of the resurrected Christ in these communal gatherings.
The earliest Eucharist likely included a complete meal, with all the participants bringing some food to share with the others (pot luck style). By the second century they were shortened to just the key actions of Jesus, the bread and wine, the prayer, and the recollection of what God did through Christ. Instead of being part of a meal, the Eucharist became part of the Sunday worship service along with scripture reading, preaching, and intercession. The Eucharist was a celebration of Christ’s resurrection, The bread and wine would be carried to anyone unable to attend whether because of illness or imprisonment. The bread and wine was considered healing.
The whole body and blood of Christ often got Christians in trouble since they were viewed as being cannibals, an accusation that early apology writers were quick to dismiss.
Over time the bread and wine themselves (rather than just the community event) took on greater importance as a method to retain connections with Christ. The bread and wine become consecrated, and as the local church community grew and became less close-knit the language surrounding the Eucharist became increasingly connected to sacrifice.
Soon the eucharistic ritual became more formalized and elaborate, and the clergy took over the performance of the ritual. Certain internal states were considered necessary for receiving the bread and wine. People in the Middle Ages still attended the rite every Sunday, but only received Communion once or twice a year, after making a confession of their sins. If you were not a member of the Church, or if you got excommunicated you could not receive communion.
Instead of being a communal meal, the Eucharist became an object of devotion. Through the words of the eucharistic prayer the bread and wine became Christ's body and blood, and so sacred and an object of distant worship. Ordinary worshipers might still be offered the bread but not the wine for fear they might spill it, and sometimes only the priest would partake at all.
So then comes the Reformation and a rejection of the idea that Christ was in any sense offered in the Eucharist, as well as for most Reformers the idea that an actual transformation took place in the bread and wine. They generally believed Christ was present spiritually only to the worthy recipient of Communion. That meant that everyone attending (well generally anyone that believed in Jesus) the rite should always receive bread and wine (or grape juice in some Protestant churches), but celebrated it only a few times a year in most Protestant churches, and was replaced by a preaching service on other Sundays.
Communion is also sometimes practiced by intinction. Intiction means that the host is dipped into the wine and eaten together.
Byzantine told me that in the Orthodox Church they use both bread and wine, and the wine is ussually fed to the worshipper from a spoon.
The HarperCollins Dictionary of Religion. 1995 by The American Academy of Religion.
Combt, Jean, How to Read Church History, Crossroad: New York, 1984