Homicide is an act in which a human, causes the death of another human. A homicide requires only a volitional act or an omission that causes the death of another, and thus a homicide may result from accidental, reckless, or negligent acts even if there is no intent to cause harm. Homicides can be divided into many overlapping legal categories, such as murder, manslaughter, justifiable homicide, assassination, killing in war, euthanasia, and capital punishment, depending on the circumstances of the death. These different types of homicides are often treated very differently in human societies; some are considered crimes, while others are permitted or even ordered by the legal system.