Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
Deliverance ministry
Though many people confuse deliverance with exorcism, they are not the same. Exorcisms are carried out through the use of various rituals of exorcism, such as the Roman Ritual, and often utilize attendant sacramentals such as holy water, while deliverance involves the ongoing counseling of the individual through various programs.