278 (Baltimore Catechism, Volume 2) What is the Sacrament of Holy Orders?
A. Holy Orders is a Sacrament by which bishops, priests, and other ministers of the Church are ordained and receive the power and grace to perform their sacred duties.
(Current Catechism) the Catechism of the Catholic Church refers to the Sacrament of Holy Orders as “the sacrament of apostolic ministry.” “Ordination” comes from the Latin word ordinatio, which means to incorporate someone into an order. During the exodus God chose the tribe of Levi as priests for the nation. Their primary duties were the offering of sacrifice and prayer for the people. Christ, in offering Himself up for the sins of all mankind, fulfilled the duties of the Old Testament priesthood once and for all.
There are three levels to this sacrament: the episcopate, the priesthood, and the diaconate”
- The Episcopate
A bishop is a man who is ordained to the episcopate by another bishop (in practice, by several bishops). He stands in a direct, unbroken line from the Apostles, a condition known as “apostolic succession.” Ordination as a bishop confers the grace to sanctify others, as well as the authority to teach the faithful and to bind their consciences. Because of the grave nature of this responsibility, all episcopal ordinations must be approved by the Pope. then he has power to administer Confirmation and Holy Orders, ordaining priests and consecrating bishops. Through the bishops, it is addressed to redactors of catechisms, to priests, and to catechists.
77 “In order that the full and living Gospel might always be preserved in the Church the apostles left bishops as their successors. They gave them their own position of teaching authority.”  Indeed, “the apostolic preaching, which is expressed in a special way in the inspired books, was to be preserved in a continuous line of succession until the end of time.” 
78 This living transmission, accomplished in the Holy Spirit, is called Tradition, since it is distinct from Sacred Scripture, though closely connected to it.
Bishops can confer the Sacrament of Holy Orders. “Confer”–that is, give or administer. So can a cardinal, if he be a bishop, and so can the Holy Father, who is always a bishop, and called bishop of Rome, while Pope of the whole Church. A diocese is the extent of country over which a bishop is appointed to rule.An archbishop is higher than a bishop, but no more spiritual power than a bishop. The district over which an archbishop rules contains several dioceses with their bishops, and is called an ecclesiastical province. The bishops in the province are called suffragan bishops, because subject in some things to the authority of the archbishop, who is also called the metropolitan, because bishop of a metropolis or chief city of the province over which he presides.The archbishop can wear the pallium, a garment worn by the Pope, and sent by him to patriarchs, primates, and archbishops. It is a band of white wool, worn over the shoulders and around the neck after the manner of a stole. It has two strings of the same material and four black or purple crosses worked upon it. It is the symbol of the plenitude of pastoral jurisdiction conferred by the Holy See.
- The Priesthood
The second level of the Sacrament of Holy Orders is the priesthood. No bishop can minister to all of the faithful in his diocese, so priests act, in the words of the Catechism of the Catholic Church, as “co-workers of the bishops.” They exercise their powers lawfully only in communion with their bishop, and so they promise obedience to their bishop at the time of their ordination. Let’s here enjoy a priestly vocation story. Pilot to Priesthood-a video of his Vocation Story. The chief duties of the priesthood are the preaching of the Gospel and the offering of the Eucharist
What defines a priest, nun or any consecrated person is the positive offering he makes of his life to Christ. He takes all he is and offers it to Christ. He lives only for him. This means fundamentally that he chooses Christ over any other human to be the center of his life (chastity), he values Christ more than any material thing and he gives these up in order to possess Him totally (poverty), and he is totally dedicated to His will and His work (obedience). The practical way the vows of chastity, poverty, and obedience are lived out will depend on the particular charism of the order or group he is called to.
The third level of the Sacrament of Holy Orders is the diaconate. Deacons assist priests and bishops, but beyond the preaching of the Gospel, they are granted no special charism or spiritual gift. In the Eastern Churches, both Catholic and Orthodox, the permanent diaconate has been a constant feature. In the West, the office of deacon was reserved to men who intended to be ordained to the priesthood. The permanent diaconate was restored in the West by the Second Vatican Council. Married men are allowed to become permanent deacons.
The terms “deacon” and “diaconate” derive from the Greek word diakonia which means “service” or “ministry.” A deacon, then, is ordained by the Church for service. Deacons provide service in three ways:
Service of the Word — this includes preaching, offering catechetical instruction, spiritual counseling, instructing catechumens, giving retreats, conducting parish renewal programs, and reaching out to alienated Catholics
Service of the Altar — Deacons’ role in the Eucharist — in addition to proclaiming the Gospel and articulating the Church’s needs in the general intercessions — is to prepare the gifts and distribute communion at the Lord’s table. Deacons may baptize children or adults, witness marriages in the name of the Church, bring Viaticum to the dying, and preside over wakes, funerals, and burial services.
Service of Charity — is as extensive as are human needs. Deacons minister in prisons and in hospitals. They visit the homebound and people in nursing homes. They serve the mentally ill, the chemically dependent, the abused and the battered, the old and the young, the abandoned, the dying and the bereaved, immigrants and refugees and the victims of racial and ethnic discrimination.