Revenge is a harmful action against a person or group in response to a grievance, be it real or perceived. It is also called payback, retribution, retaliation or vengeance; it may be characterized as a form of justice, an altruistic action which enforces societal rules and which is based on a deep rooted evolutionary instinct that helped humanity by implementing social cohesion in a subtle way.^{[citation needed][neutrality is disputed]}

Some societies believe that the punishment in revenge should be more than the original injury. For example, a poll of over 1,800 Americans showed that about 40% would support the death penalty for child rape.

Detractors argue that revenge is a simple logical fallacy, of the same design as "two wrongs make a right". Some assert that the Hebrew Bible's concept of reciprocal justice "an eye for an eye" (Exod. 21:24) validates the concept of proportionate revenge, in which there would be a simple 'equality of suffering'; however Rabbinic law states this verse indicates a person should provide a monetary payment for the eye or tooth that was damaged, and does not require the assailant to receive physical damage. This view confounds the concepts of "justice" and "revenge," and disregards the fact that "eye for an eye" justice was a philosophical advance on the normative practice of the day (see blood feud, infra) and that Judaic scripture elsewhere prescribes “Do not seek revenge . . . love your neighbor as yourself” (Leviticus 19:18). Also, the Hebrew Bible illustrates the concept that '"vengeance is mine" says the Lord' (Deut. 3:25, cf., in the NT, Rom. 12:19).

Pornography or porn is the explicit portrayal of sexual subject matter. Pornography may use a variety of media, including books, magazines, postcards, photos, sculpture, drawing, painting, animation, sound recording, film, video, and video games. The term applies to the depiction of the act rather than the act itself, and so does not include live exhibitions like sex shows and striptease. A pornographic model poses for still photographs. A pornographic actor or porn star performs in pornographic films. If dramatic skills are not involved, a performer in porn films may be also be called a model.

A distinction is often made between erotica (the portrayal of sexuality with high-art aspirations, focusing also on feelings and emotions) and pornography (the depiction of acts in a sensational manner, with the entire focus on the physical act, so as to arouse quick intense reactions).

Pornography has often been subject to censorship and legal restraints to publication on grounds of obscenity. Such grounds and even the definition of pornography have differed in various historical, cultural, and national contexts. With the emergence of social attitudes more tolerant of sexuality and more specific legal definitions of obscenity, an industry for the production and consumption of pornography arose in the latter half of the 20th century. The introduction of home video and the Internet saw booms in a worldwide porn industry that generates billions of dollars annually.