Corpus Christi is a Christian feast in honour of the Holy Eucharist. It was originally assigned to the Thursday following Trinity Sunday, thereby mirroring Holy Thursday, the Thursday of Holy Week, the day on which Christians commemorate The Last Supper of Jesus Christ and his apostles, seen as the first Holy Eucharist. Many English-speaking countries celebrate the Feast of Corpus Christi on the Sunday after Trinity Sunday - on the Sunday after the traditional Thursday celebration in other countries. It is customary on this day, after Mass, to hold processions which is often outdoors with the Host followed by Benediction of the Blessed Sacrament. Corpus Christi is a public holiday in some traditionally Catholic countries such as Austria, parts of Germany and Switzerland, Brazil, Dominican Republic, Croatia, Poland, Trinidad and Tobago and Portugal. In very truth it is a marvellous thing that God rained manna on the fathers, and fed them with daily food from heaven; so that it is said, "So man did eat angels' food." But yet all those who ate that food died in the wilderness, but that food which you receive, that living Bread which came down from heaven, furnishes the substance of eternal life; and whosoever shall eat of this Bread shall never die, and it is the Body of Christ.
Researched from Wikipedia