Punishment is the authoritative imposition of an undesirable or unpleasant outcome upon a group or individual, in response to a particular action or behaviour that is deemed unacceptable or threatening to a norm. The unpleasant imposition may include a fine, penalty, or confinement, or be the removal or denial of something pleasant or desirable. The individual may be a person, or even an animal. The authority may be either a group or a single person, and punishment may be carried out formally under a system of law or informally in other kinds of social settings such as within a family. Negative consequences that are not authorised or that are administered without a breach of rules are not considered to be punishment as defined here. The study and practice of the punishment of crimes, particularly as it applies to imprisonment, is called penology, or, often in modern texts, corrections; in this context, the punishment process is euphemistically called "correctional process". Research into punishment often includes similar research into prevention.Justifications for punishment include retribution, deterrence, rehabilitation, and incapacitation. The last could include such measures as isolation, in order to prevent the wrongdoer's having contact with potential victims, or the removal of a hand in order to make theft more difficult. Of the four justifications, only retribution is part of the definition of punishment and none of the other justifications is a guaranteed outcome, aside from obvious exceptions such as an executed man being incapacitated with regard to further crimes.If only some of the conditions included in the definition of punishment are present, descriptions other than "punishment" may be considered more accurate. Inflicting something negative, or unpleasant, on a person or animal, without authority is considered either spite or revenge rather than punishment. In addition, the word "punishment" is used as a metaphor, as when a boxer experiences "punishment" during a fight. In other situations, breaking a rule may be rewarded, and so receiving such a reward naturally does not constitute punishment. Finally the condition of breaking (or breaching) the rules must be satisfied for consequences to be considered punishment.Punishments differ in their degree of severity, and may include sanctions such as reprimands, deprivations of privileges or liberty, fines, incarcerations, ostracism, the infliction of pain, amputation and the death penalty. Corporal punishment refers to punishments in which physical pain is intended to be inflicted upon the transgressor. Punishments may be judged as fair or unfair in terms of their degree of reciprocity and proportionality. Punishment can be an integral part of socialisation, and punishing unwanted behaviour is often part of a system of pedagogy or behavioral modification which also includes rewards.