Witchcraft, in historical, anthropological, religious, and mythological contexts, is the alleged use of supernatural or magical powers. A witch (from Old English wicca masculine, wicce feminine) is a practitioner of witchcraft. Historically, it was widely believed in early modern Christian Europe that witches were in league with the Devil and used their powers to harm people and property. Particularly, since the mid-20th century, "bad" and "good" witchcraft are sometimes distinguished, the latter often involving healing. The concept of witchcraft as harmful is normally treated as a cultural ideology, a means of explaining human misfortune by blaming it either on a supernatural entity or a known person in the community.

Beliefs in witchcraft, and resulting witch-hunts, existed in many cultures worldwide and still exist in some today, mostly in Sub-Saharan Africa (e.g. in the witch smellers in Bantu culture). Historically these beliefs were notable in Early Modern Europe of the 14th to 18th century, where witchcraft came to be seen as a vast diabolical conspiracy against Christianity, and accusations of witchcraft led to large-scale witch-hunts, especially in Germanic Europe.

War is an organized, armed, and often a prolonged conflict that is carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. War should be understood as an actual, intentional and widespread armed conflict between political communities, and therefore is defined as a form of political violence. The set of techniques used by a group to carry out war is known as warfare. An absence of war (and other violence) is usually called peace.

In 2003, Nobel Laureate Richard E. Smalley identified war as the sixth (of ten) biggest problems facing the society of mankind for the next fifty years. In the 1832 treatise On War, Prussian military general and theoretician Carl von Clausewitz defined war as follows: "War is thus an act of force to compel our enemy to do our will."

While some scholars see warfare as an inescapable and integral aspect of human culture, others argue that it is only inevitable under certain socio-cultural or ecological circumstances. Some scholars argue that the practice of war is not linked to any single type of political organization or society. Rather, as discussed by John Keegan in his History of Warfare, war is a universal phenomenon whose form and scope is defined by the society that wages it. Another argument suggests that since there are human societies in which warfare does not exist, humans may not be naturally disposed for warfare, which emerges under particular circumstances. The ever changing technologies and potentials of war extend along a historical continuum. At the one end lies the endemic warfare of the Paleolithic^{[citation needed]} with its stones and clubs, and the naturally limited loss of life associated with the use of such weapons. Found at the other end of this continuum is nuclear warfare, along with the recently developed possible outcome of its use, namely the potential risk of the complete extinction of the human species.