What is a Sacrament?

A sacrament is an efficacious sign of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us through the work of the Holy Spirit.  The sacraments are seven in number.

Who can receive the sacraments?

Having become a member of the Church, the person baptized belongs no longer to himself, but to him who died and rose for us. From now on, he is called to be subject to others, to serve them in the communion of the Church, and to "obey and submit" to the Church's leaders, holding them in respect and affection. Just as Baptism is the source of responsibilities and duties, the baptized person also enjoys rights within the Church: to receive the sacraments, to be nourished with the Word of God and to be sustained by the other spiritual helps of the Church.   "Reborn as sons of God, [the baptized] must profess before men the faith they have received from God through the Church" and participate in the apostolic and missionary activity of the People of God.

Who gave us the sacraments?

"Adhering to the teaching of the Holy Scriptures, to the apostolic traditions, and to the consensus . . . of the Fathers," we profess that "the sacraments of the new law were . . . all instituted by Jesus Christ our Lord."

Jesus' words and actions during his hidden life and public ministry were already salvific, for they anticipated the power of his Paschal mystery. They announced and prepared what he was going to give the Church when all was accomplished. The mysteries of Christ's life are the foundations of what he would henceforth dispense in the sacraments, through the ministers of his Church, for "what was visible in our Savior has passed over into his mysteries."

Sacraments are "powers that comes forth" from the Body of Christ, which is ever-living and life-giving. They are actions of the Holy Spirit at work in his Body, the Church. They are "the masterworks of God" in the new and everlasting covenant.

Are the Sacraments Biblical? (from Mark Hart)

One of the greatest myths and misconceptions about our Catholic faith is that the seven Sacraments are not found anywhere in Scripture. Let’s get right to the point…that assertion is absolutely false. At times over the years, certain people have “freaked out” because the Bible doesn’t "name" sacraments, (confirmation, for instance) or give explicit instructions as to what happens at some of them. The Sacraments, however, were initiated by Christ and instituted by Him, they were then formally carried out by His apostles and their successors, the Bishops. All of the Sacraments have a Biblical basis, intrinsically and implicitly. A Sacrament is “an outward sign, instituted by Christ, to bring grace”. Always remember that the Catholic Church is founded on Sacred Scripture and Sacred Tradition. The two work hand-in-hand to make known to us the fullness of God’s revelation, through the guidance and inspiration of the Holy Spirit. In fact, the need to adhere to both Scripture AND Tradition is itself, a biblical truth and scriptural command, “Therefore, brothers, stand firm and hold fast to the traditions that you were taught, either by an oral statement or by a letter of ours.” - 2 Thessalonians 2:15

All information unless noted by () is taken from The Catechism of the Catholic Church