Catechism of the Catholic Church
1671 Among sacramentals blessings (of persons, meals, objects, and places) come first. Every blessing praises God and prays for his gifts. In Christ, Christians are blessed by God the Father "with every spiritual blessing." 177 This is why the Church imparts blessings by invoking the name of Jesus, usually while making the holy sign of the cross of Christ.
1672 Certain blessings have a lasting importance because they consecrate persons to God, or reserve objects and places for liturgical use. Among those blessings which are intended for persons—not to be confused with sacramental ordination—are the blessing of the abbot or abbess of a monastery, the consecration of virgins and widows, the rite of religious profession and the blessing of certain ministries of the Church (readers, acolytes, catechists, etc.). The dedication or blessing of a church or an altar, the blessing of holy oils, vessels, and vestments, bells, etc., can be mentioned as examples of blessings that concern objects.
1673 When the Church asks publicly and authoritatively in the name of Jesus Christ that a person or object be protected against the power of the Evil One and withdrawn from his dominion, it is called exorcism. Jesus performed exorcisms and from him the Church has received the power and office of exorcizing. 178 In a simple form, exorcism is performed at the celebration of Baptism. The solemn exorcism, called "a major exorcism," can be performed only by a priest and with the permission of the bishop. The priest must proceed with prudence, strictly observing the rules established by the Church. Exorcism is directed at the expulsion of demons or to the liberation from demonic possession through the spiritual authority which Jesus entrusted to his Church. Illness, especially psychological illness, is a very different matter; treating this is the concern of medical science. Therefore, before an exorcism is performed, it is important to ascertain that one is dealing with the presence of the Evil One, and not an illness. 179
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.