Homicide is when one person kills (causes the death of) another person. Homicide is often a crime but sometimes is is not. If the killer wanted to cause death, it can be a crime called murder. If the killer did not want to cause death, but had no care for their own behavior, it can be a crime called manslaughter. Fighting to keep oneself safe from harm is called self-defense. If a person needed to kill for self-defense, it is usually not a crime. If a person killed in self-defense when they did not need to kill, it may be a crime.