Human sacrifice is the act of killing one or more human beings, usually as an offering to a deity, as part of a ritual. Human sacrifice has been practiced in various cultures throughout history. Victims were typically ritually killed in a manner that was supposed to please or appease gods, spirits or the deceased, for example as a propitiatory offering or as a retainer sacrifice when a king's servants are killed in order for them to continue to serve their master in the next life. Closely related practices found in some tribal societies are cannibalism and headhunting.
By the Iron Age, with the associated developments in religion (the Axial Age), human sacrifice was becoming less common throughout the Old World, and came to be looked down upon as barbaric in classical antiquity. In the New World, however, human sacrifice continued to be widespread to varying degrees until the European colonization of the Americas.
In modern times, even the practice of animal sacrifice has virtually disappeared from all major religions (or has been re-cast in terms of ritual slaughter), and human sacrifice has become extremely rare. Most religions condemn the practice, and modern secular laws treat it as murder. In a society which condemns human sacrifice, the term ritual murder is used.
Human sacrifice is distinguished from infanticide. Infanticide is deliberately causing the death of an unwanted infant or young child, but without a ritualistic or religious purpose.
The idea of human sacrifice has its roots in deep prehistory, in the evolution of human behaviour. From its historical occurrences it seems mostly associated with neolithic or nomadic cultures, on the emergent edge of civilization.