Exorcism
In Christianity, exorcism is the practice of casting out demons. In Christian practice the person performing the exorcism, known as an exorcist, is often a member of the Christian Church, or an individual thought to be graced with special powers or skills. The exorcist may use prayers and religious material, such as set formulas, gestures, symbols, icons, amulets, etc. The exorcist often invokes God, Jesus and/or several different angels and archangels to intervene with the exorcism. Protestant Christian exorcists most commonly believe the authority given to them by the Father, Son, and Holy Spirit (the Trinity) is the source of their ability to cast out demons.
Exorcist
The Catholic Church's Rite of Exorcism was revised in 1999. Paragraph 13 of its introduction states that a priest can be appointed by the local Bishop either for a single act of exorcism, or to the permanent position of 'exorcist'. The Rite then specifies that whenever it uses the word "exorcist" without qualification, it indicates a priest mandated in this way.
Among notable exorcists, Gabriele Amorth served as chief exorcist of the Diocese of Rome; he was the founder of the International Association of Exorcists.