All members of the Church participate in the priesthood of all believers through Baptism. However, some men are called to serve Jesus and the Church today through the celebration of the Sacrament of Holy Orders. Through their leadership in the Church, they help continue Jesus’ presence on earth in the tradition of the apostles. There are three levels of participation in the Sacrament of Holy Orders: as bishop, as priest (from presbyter, which is Greek for “elder”), and as deacon.
In the rite of Ordination for priests, the candidate receives the Sacrament of Holy Orders, with a bishop laying his hands on the head of the candidate and saying a prayer asking for the outpouring of the Holy Spirit. In one part of the rite, the candidate lies in front of the altar while the Litany of the Saints is sung or recited. In another part of the rite, a priest’s hands are anointed with chrism.
From the United States Conference of Catholic Bishops:
Ordination to the priesthood is always a call and a gift from God. Christ reminded his Apostles that they needed to ask the Lord of the harvest to send laborers into the harvest. Those who seek priesthood respond generously to God’s call using the words of the prophet, “Here I am, send me” (Is 6:8). This call from God can be recognized and understood from the daily signs that disclose his will to those in charge of discerning the vocation of the candidate.