Witchcraft has variegated historical, anthropological, religious and mythological perspectives however, refers to use of supernatural or magical powers generically.
The term "witchcraft" can have positive or negative connotations depending on cultural context; for instance, in post-Christian European cultures it has historically been associated with evil and the Devil, while most contemporary people who self-identify as witches see it as beneficent and morally positive.

The majority of people identified as practitioners of witchcraft in history were women. Likewise, in myth the stereotype is female. The term witch is typically feminine, masculine equivalents include wizard, sorcerer, warlock and magician.

Source: Wikipedia, Occultastrology

Black Magic through body by-products
Black Magic through Earth-dust
Black Magic through undergarments
Black Magic through Telepathy and Hypnotism

Black Magic through body by-products

If a photograph of the person on whom the magical effect is to betransferred, is not available, the person's nail, body product likehandkerchief, vest, shirt or pant, or a piece thereof or anything else like his or her fountain pen and cigarette case can be used, even thecomb and towel can cause a big damage to the person if these items aremisused. The tooth of a person is the easiest way of affecting blackmagic on him or her.

Black Magic through Earth-dust

The dust of the Earth from the room or place where one is living oruses more often can be collected by a wet piece of cloth and it can bemagically treated for or mistreated against.

Black Magic through undergarments

In certain cases even the underwear or undergarment can be used formagical purposes to achieve certain successes or causing certaindamages in relationship between husband and wife, or lover and beloved, or employer and employee. In some cases, only that underwearis preferred, which was earlier used during the worldly enjoymentbetween man and woman.

Black Magic through Telepathy and Hypnotism.

The use of "magic words" ,"magical rod", or ritual tools invoke or evoke the spirit, in fact such use of words or wand or rod or ritualtool are used in commanding the spirits, and they become activatedwithin a short while..

As regards defending the negative magical effect, mysterious godly symbols or signs are used to keep away the spirits and the blackmagic. Similarly there is a method of telepathy and hypnotism whichcan be employed for magical results, good or bad, health or otherwise.These have a specific procedure which one has to adopt to achieve the preferred results.