A necromancy is a form of magic in which the practitioner seeks to summon “operative spirits” or “spirits of divination”, for multiple reasons, from spiritual protection to wisdom. The word necromancy derives from the Greek (nekrós), “dead”, and (manteía), “prophecy”.
However, since the Renaissance, necromancy (or nigromancy) has come to be associated more broadly with black magic and demon-summoning in general, sometimes losing its earlier, more specialized meaning. By popular etymology, nekromantia became nigromancy “black arts”, and Johannes Hartlieb (1456) lists demonology in general under the heading.
Necromancy is used colloquially in fantasy entertainment to mean raising the dead. Many heavy metal and death metal bands have a prefix necro to indicate the mood of their music.