Witchcraft is the practise of any Magickal Art from any religious or spiritual system, regardless of alignment or intent.
This can include the very diverse and even opposing forces of the religious doctrines of Wicca, Druidism, many sects of Hinduism, Sufism(a branch of Islam), Asatru, Satanism; Also included could be certain rites and practices of the Golden Dawn, Ordo Templi Orientis, Temple of Set, Freemasonry and
the Roman Catholic Church (see Transmutation of the Holy Eucharist).
When
the Roman Catholic Church was in control of Europe, simply being accused of Witchcraft was enough to have you summarily executed on the charge of Heresy. This Witch-Craze spilled over into Protestant territories in Europe and even into the
United States for a brief period. In Europe, it was quite common for Roman Catholics to accuse Protestants of Witchcraft and for Protestants to do the same of Roman Catholics. Caught
in the middle of all this what would seem today as "in-fighting" within
Christianity were the Nature-Based or "Pagan" religions of Europe of which Wicca is a revivalist product.
Wicca has the best claim to the title "Witch" due to the etymology of the words, but it is not incorrect for practitioners of other Craft religions to identify themselves in the same.
Witchcraft can be both beneficial or detrimental, depending on the Magical Intent of the practitioner and because of this, Witchcraft in itself is seen today as "evil" by many religious groups; however, it should be noted that Witchcraft is merely a tool and has no more goodness or evilness as a car or a hammer -- it depends entirely upon what it is used for and the person weilding it.