Homicide is the intentional killing of another person by a human being. It is part of the continuum of violence, and rates vary between cultures. Several theories have been proposed to explain why people kill one another. Some suggest that homicide is a natural response to contexts of conflict and that it was adaptive for our ancestors.
Homicide can be classified into many overlapping categories, including murder, manslaughter, euthanasia, killing in war (either as a crime or following the laws of war), and justifiable homicide. Murder is the most serious form of homicide, and carries severe penalties. First-degree murder is premeditated and unlawful, while second-degree murder lacks premeditation and occurs in the heat of the moment.
Manslaughter is the killing of a person that does not involve malice or intent. Voluntary manslaughter is when there are factors that mitigate rather than excuse the killing, such as provocation. Justifiable homicide is the killing of another person in situations that are legally justified.
Prevention of homicide can be accomplished through education, counselling, and support for victims. Addressing domestic violence, especially through the implementation of sex offender programs, and reducing access to weapons—especially firearms—for those with a history of violent behaviour or mental illness can help reduce homicides. Strengthening gun control laws can also reduce homicides, as can addressing youth violence by providing at-risk youth with after-school programs and other social supports. Lastly, efforts to improve health care access for those with mental illnesses can also reduce homicides associated with these conditions.