What is a Sacrament?
A Sacrament is an outward sign instituted by Christ to give grace.

From the Catechism of the Catholic Church #1210
"Christ instituted the sacraments of the new law. There are seven: Baptism, Confirmation, the Eucharist, Penance, the Anointing of the Sick, Holy Orders and Matrimony. The seven sacraments touch all the stages and all the important moments of Christian life: they give birth and increase, healing and mission to the Christian's life of faith. "