Demonology is the study of demons or beliefs about demons, especially the methods used to summon and control them. The original sense of "demon", from the time of Homer onward, was a benevolent being, but in English the name now holds connotations of malevolence. (In order to keep the distinction, when referring to the word in its original Greek meaning English may use the spelling "Daemon" or "Daimon".)
Demons, when regarded as spirits, may belong to either of the classes of spirits recognized by primitive animism. That is to say, they may be human, or non-human, separable souls, or discarnate spirits which have never inhabited a body. A sharp distinction is often drawn between these two classes, notably by the Melanesians, several African groups, and others. The Arab jinn, for example, are not reducible to modified human souls. At the same time these classes are frequently conceived as producing identical results, e.g. diseases.
The word is from Greek , daimōn, "divinity, divine power, god"; and , .
According to some societies, all the affairs of life are supposed to be under the control of spirits, each ruling a certain "element" or even object, and themselves in subjection to a greater spirit. For example, the Inuit are said to believe in spirits of the sea, earth and sky, the winds, the clouds and everything in nature. Every cove of the seashore, every point, every island and prominent rock has its guardian spirit. All are potentially of the malignant type, to be propitiated by an appeal to knowledge of the supernatural. Traditional Korean belief posits countless demons inhabit the natural world; they fill household objects and are present in all locations. By the thousands they accompany travelers, seeking them out from their places in the elements.
In ancient Babylon, demonology had an influence on even the most mundane elements of life, from petty annoyances to the emotions of love and hatred. The numerous demonic spirits were given charge over various parts of the human body, one for the head, one for the neck, and so on.