The word conjuration or summoning (from Latin 'conjuratio', 'conjurare', to swear together) can be interpreted in several different ways: as an invocation or evocation (the latter in the sense of binding by a vow); as an exorcism; or as an act of illusionism. The word is often used synonymously with "invocation", although the two are not synonyms. Conjuration is also refered as forceful evocation because against the will of the spirit, typical for the grimoires. One who performs conjurations is called a conjurer or conjuror.

As an invocation, a conjuration is the act of summoning one or more spirits with a pre-determined purpose by means of a charm. This typically means that the conjurer will perform some ritual to call upon the spirit.

The calling forth of spirits is a vital element of most traditions of magic all over the world. In the Western esoteric tradition, the classical example of this idea is in the magic of the grimoires, and particularly the Goetia.

Rituals and preparation

Some conjurations have as a requisite a previous ritual of purification of body, mind and soul to attract the spirit or avoid the danger this entity could represent.
 

Depending on the individual magical system, spirits are often evoked into some sort of medium, such as a pillar of smoke, a crystal ball, a fetish, or a human volunteer who is expected to become possessed by the spirit. In most magical systems (one exception being Enochian Magic), even spirits not evoked into a particular medium are expected to remain close to the place the magician evoked them to.

Some think that for a better result the conjurer must wear special clothes and/or ornaments, and amulets for attraction and/or protection. Magic symbols drawn on the floor and/or altar and embroidered on the clothes are often used, having each one a specific purpose. The hour of the day or night and the planetary aspects (astrological configuration of the zodiac) are considered important, depending on the purpose of the conjuration.

A special atmosphere is generally preferred in the room or place in which the ritual is going to be performed, using specific aromatic resins and herbs (incense, myrrh, etc.), and lighting the place with candles or torches if possible.

The text of the charms to be recited to conjure the spirit varies considerably from simple sentences to complex paragraphs with plenty of magic words. The language usually is that of the conjurer's, but since the Middle Ages in Western tradition, Latin was the most common (although many texts have been translated into other languages).

The conjuration of the ghosts or souls of the dead for the purpose of divination is called necromancy.

When it is said that a person is calling upon or conjuring misfortune or disease, it is due to the ancient belief that personified diseases and misfortune as evil deities, spirits or demons that could enter a human or animal body.

It is traditionally believed by many, particularly in Christian societies, that magic, and thus conjuration, is an inherently evil practice. According to these beliefs, conjurers summon demons or other evil spirits to cause harm to people or things, to obtain favors from them, or simply to enter servitude to such beings. The belief in similarly minded conjurers also exists in belief systems in which magic is not inherently evil, although in these cultures these "black magicians" are not the rule and have opposition among more traditional magicians.