Murder is the unlawful killing of another human without justification or valid excuse committed with the necessary intention as defined by the law in a specific jurisdiction. This state of mind may, depending upon the jurisdiction, distinguish murder from other forms of unlawful homicide, such as manslaughter. Manslaughter is killing committed in the absence of malice, such as in the case of voluntary manslaughter brought about by reasonable provocation, or diminished capacity. Involuntary manslaughter, where it is recognized, is a killing that lacks all but the most attenuated guilty intent, recklessness.
Most societies consider murder to be an extremely serious crime, and thus believe that a person convicted of murder should receive harsh punishments for the purposes of retribution, deterrence, rehabilitation, or incapacitation. In most countries, a person convicted of murder generally receives a long-term prison sentence, a life sentence, or capital punishment. Some countries, states, and territories, including the United Kingdom and other countries with English-derived common law, mandate life imprisonment for murder, whether it is subdivided into first-degree murder or otherwise.
