Official Roman Catholic doctrine regarding Holy Communion,states that the substance of the bread is changed into the substance of the body, and the substance of the wine is changed in to the substance of the blood. This doctrine is called "Transubstantiation". In other words, it looks like bread and wine but actually IS "the body and blood of Christ". Another way of expressing this, it is the "Real Presence" of Christ in the "elements" of bread of wine. this doctrine was rejected by most reformers in the 16th Century......Note, most Anglicans (Episcopalians) still accept a "Real Presence" of Christ in the sacrament, but they don't define how or what...but that, Christ is "really present" when the bread is blessed, broken and shared, and the cup of wine is blessed and shared..they don't define the how, it is considered a mystery, similar to the way Eastern Orthodoxy approaches this topic. This explains why you will see tabernacles where the sacrament is "reserved" in Roman Catholic and most Anglican churches. The Lutherans also believe in a "Real Presence" in the sacrament but to best of my knowledge, do not "reserve" the sacrament. The Lutheran belief is closer to the Anglicans, than to the Roman Catholics. Note..Roman Catholics will literally worship the elements, e.g during service of benediction, where the consecrated bread, albeit the "Body of Christ" is placed in a large golden stand, known as a Monstrance for a blessing and adoration by the faithful. This is unique to the Roman Catholics, although I've read there are some very "Catholic" leaning Anglicans who observe this practice, but this would certainly not be the norm. For most of Protestant christendom, the bread and wine (or grape juice) are symbols or represent the body and blood of Christ, but NO Real Presence in the elements is assumed or believed.