Westerners think of Wiccans and women with broomsticks often times when we consider "witchcraft." Even modern concepts of the "witch" includes women who recite spells and perhaps concoct potions from herbs and such.
While there are those in western society that probably take it seriously, I think in reality most just pretend to take it seriously. It's more of a counter-culture movement than actual religious practice.
However, there are cultures in the world where witchcraft is taken very seriously and the believers kill or die for it. In many West African nations, the indiginous populations blame just about anything bad that happens on witchcraft, and a witch can be either male or female. There, "witchcraft" is defined as a supposed psychic emanation from a witchcraft substance which is believed to cause injury to health and property. Witchcraft, to cultures like the Azande, Nupe, Gwari, or the Mesakin is evil.
A 'witchcraft substance' or mangu is a material in the bodies of certain persons. It is "discovered" in the autopsies of the dead and is "diagnosed" by oracles in the living, and can be passed from father to son.
Many West African cultures believe that the souls of witches sail through the night on the winds, inflicting pain on people. Pregnant women are particularly at risk.
In a land where misfortune and calamity can come to a person or family in the form of disease, famine, drought, infection, and birth problems because of inadequate infrastructures of health care, sanitation, etc., its easy to imagine the need to blame misfortunes such as still born children on the souls of witches who attacked the baby in the womb while the mother made a trip to the latrine at night.
Withcraft exists in other cultures as well. The Navajo believe that witches do much of the same things the West Africans do: bring misfortune and calamity to their enemies. The Navajo have a taboo against speaking of these witches in public, though they all know who they are. Reportedly, there are clans of Navajo that are born into witchcraft and learn to shape-shift into other creatures like coyotes or wolves or owls. The sighting of a lone coyote on one's property, particularly one that acts peculiar, is considered to be evidence that a Navajo witch has visited and is considered a warning.
Oh... the Navajo witch is called a skinwalker, or in the Navajo language, yenaldlooshi.
It also occurs to me that the traditional concept of the old woman flying on a broomstick also probably has some basis in fact. European witches of medieval times once used a species of Banisteriopsis to attain an altered or trance state in which they could see visions, obtain information, etc. Perhaps they felt the sensation of "flying" and the method of ingesting the Banisteriopsis was to apply it to the broom stick and 'ride' it. The vaginal tissues being thin-walled, the drug was easily absorbed into the blood stream.
I typed all that from memory and the West African witchcraft references come mostly from E.E. Evans-Pritchard's work, perhaps Victor Turner as well. I have sources for the Navajo & European witchcraft information somewhere in my notes if anyone wants citations.