A sacrament is an outward sign, instituted by Christ, to give grace.  The purpose of the Sacraments is to make people holy, to build up the Body of Christ and finally, to give worship to God.  Since Sacraments are signs, they also have a teaching function.  The Sacraments nourish and strengthen our faith and they impart grace.  As we celebrate the Sacraments, we worship God and practice charity.  All the Sacraments flow from the life and ministry of Jesus as recorded in the New Testament.  Jesus himself instituted all the sacraments (CCC 1114), either by explicit command or by His work or teaching.