Witchcraft, traditionally, the exercise or invocation of supernatural powers to manipulate unknown energy. Witchcraft practices typically involve meditation, rituals and much more. There is a common belief that witches worship the devil- this is a far fetched false statement! In reality, witches worship mother nature. 

You probably first heard about witchcraft through the stories of the salem witch trials- The Salem witch trials were a series of hearings and prosecutions of people accused of witchcraft in colonial Massachusetts between February 1692 and May 1693. 

One of the most widely known characteristic of a witch is the ability to cast a spell, spell being the word used to signify the means employed to carry out a magical action. A spell could consist of a set of words, a formula or verse, or a ritual action, or any combination of these. Spells traditionally were cast by many methods, such as by the inscription o frunes or sigals on an object to give that object magical powers; by the immolation or binding of a wax or clay image of a person to affect them magically; by the recitation ofincantations; by the performance of physical rituals; by the employment of magical herbs as amulets or potions; by gazing at mirrors, swords or other specula  for purposes of divination; and by many other means.