Corpus Christi means the Body of Christ, but why do we celebrate one day specifically called Corpus Christi? It is basically a celebration of the fact that the body and blood of Jesus Christ, the Son of God, is present in what appears to be bread and wine during the Eucharist, a re-enactment of the Last Supper, the final meal that Jesus Christ shared with his disciples.
“I am the living bread that came down from heaven; whoever eats this bread will live forever”