Initiation into the Church, by immersion in water, of people old enough to understand the ceremony/rite and who have made the decision to live a Christian life
Catholic Church: Transubstantiation - the bread and wine become the actual body and blood of Jesus. Christ's presence in them is known as the 'real presence'. The Eucharist is the 'source and summit' of Christian life (Catechism of the Catholic Church).
Protestant Church: The bread and wine are symbolic of the body and blood of Jesus
Orthodox Church: Accept the Eucharist as a sacrament though it is not possible to explain the transubstantiation as it is a divine mystery
Quakers: Do not practice or observe the Eucharist - or any other Sacrament - in any form. Instead, they try to find the sacred in all of life