The term black witch is a relatively modern creation generally used to distinguish between "good" and "bad" witches. These terms are used subjectively, but in general, good or "white" witches use magic in a helpful, constructive manner (see also: Wiccan Rede), black witches use it in a harmful and/or destructive manner. Many modern Pagans consider magic itself to be neither good nor evil, and thus this distinction describes the way in which a given witch uses magic, rather than the kind of magic used.
The phrase "black witch" appeared in common usage as an antonym to "white witch". Since the word "witch" itself has long had connotations of evil-doing and perceived connections to Satanism, the phrase would until recently have been considered redundant.
