Exorcism is the practice of evicting or destroying spiritual entities. The actual existence of spirits is a matter much religious debate, but in most cultures where such things are believed in, exorcism is also a part of the belief system. The person performing the exorcism is said to be an exorcist.
In some parts of Christianity, demons are said to be able to possess humans. In order to force the demon to leave the body of the victim, an exorcism is performed.
At places where belief in ghosts prevail, a ghost can be driven from a haunt (often a house, manor or castle) by an exorcism.
The exorcist is often a member of the local clergy, thought to be able to assail the spirits with divine help, or a magician of some sort.
In the past eight years, there have been at least five exorcism-related deaths in the United States:
For a broader discussion of demonic activity and Christians, see spiritual warfare.
Film: The Exorcist (1973), and its sequels.