The Mass or Eucharist is a Christian rite which is a reenactment of the Last Supper. The Bible gives this description:
And as they were eating, Jesus took bread, and blessed it, and broke it, and gave it to the disciples, and said, Take, eat; this is my body.
And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the new testament, which is shed for many for the remission of sins.
But I say unto you, I will not drink henceforth of this fruit of the vine, until that day when I drink it new with you in my Father's kingdom.[1]
"Mass" is the customary Roman Catholic term for the whole of the worship gathering in which the sacrament of the Eucharist is celebrated, from the Latin phrase spoken at the end, "ite missa est" (literally, "it is—go (missa"). The term is used only occasionally by Protestants, and those Protestants who consider themselves to be Evangelicals or Fundamentalists never use the term. In Protestant churches, Sunday gatherings are usually called "worship services," and the actual Communion celebration is called the Lord's Supper, and sometimes the Eucharist.
Because Protestants reject certain beliefs that are inherent in the Catholic Mass—for example, transubstantiation and the Mass as an act by which a sacrifice is offered—the term "Mass" is usually avoided by them in order that there be no implication that their churches agree with the Roman Catholic Church on these controversial matters.