We Catholics are different because we take Jesus Christ at His word. We believe that Jesus gave us His own body and blood in the special sacrament we call the Holy Eucharist. We actually believe that Jesus is really present in this sacrament! For us, the Holy Eucharist is not just a symbol. It is not just a memory. It is not just a promise. It is really Jesus Christ. The Holy Eucharist is not some ‘thing’. It is some ‘one’. It is Jesus, our Lord and our God. This is what we mean by the Catholic doctrine of the Real Presence of Christ in the Eucharist. This is why we call the Holy Eucharist “the Blessed Sacrament”.
Catholics believe that Transubstantiation occurs at every mass, and this is the change of the whole substance of bread into the substance of the Body of Christ and of the whole substance of wine into the substance of his Blood.