Ordination is the setting apart of some within the Body of Christ whose task is to exercise the special functions of Bishops, Priests and Deacons. These are the three 'orders' which go back in history to apostolic times _ the early Church of the New Testament era, and which have been the means of guarding the content of the faith of the Church throughout the ages.
This is particularly the function of the Episcopate (Bishops) who are regarded as successors of the Apostles. The sacrament of ordination has a special place within the sacramental structure as a whole, for it confers the authority and grace for the ministration of all the other sacraments by those who are called to this special ministry in the Church and to whom is entrusted the cure of souls, the care of the community of faith.
Again, the laying on of hands of the Bishop and the grace of the Holy Spirit, here for specific tasks, are the visible and spiritual aspects in this sacrament.