Transubstantiation is a doctrine in the Catholic Church that explains the change that occurs during the celebration of the Eucharist. According to this belief, the bread and wine used in the sacrament become the actual body and blood of Jesus Christ, while retaining their original appearance and properties. This transformation is believed to happen at the moment of consecration by the priest. The concept is rooted in the teachings of Jesus at the Last Supper, where he instructed his disciples to eat and drink in remembrance of him. Transubstantiation emphasizes the real presence of Christ in the Eucharist, making it a central element of Catholic worship and faith.