Magic is magic. Like knowledge, its use depends on the person using it and their intentions. Energy exists everywhere and can be harnessed and given instruction for any intended use by our thoughts and intentions. When constant thought intention and directed energy is placed on a specific type of energy it takes form. It is intelligent. 

In this human experience linear time is a necessary illusion to maintain order. That being said, as one chooses to incarnate into a human experience they share in common collective experiences as well as the reality they create as an individual awareness within the greater collective mind. Over "time" there has been many egregores created by the repeated energy toward certain thoughts. These egregores are collections of energy that represent particular emotions, thoughts, people, or archetypal forces. 

 Black magic or dark magic is the use of some of these energies for a negative purpose. Black magic is used to help or hook others by performing certain rituals, animal or human entity sacrifice, paranormal activities, by controlling spirits & force, that evil spirits to fulfill their commands, bewitchment, tantric kriyas, tantra mantra, tantra puja, etc. Mainly it becomes black when it is intended to violate another persons free will or impede on their chosen life experience because the magician or sorcerer believes that their will is more important than that of the other individual. Ego.

 It is generally used by unhappy, vengeful, spiteful, malicious people for malevolent acts. People use pins and needles, lemon, hair, blood, urine, nail clippings, voodoo dolls, cursed spells, skulls and bones, unwashed clothes, etc. in black magic.