Pornography ???

Pornography or porn is the explicit depiction of sexual subject matter with the sole intention of sexually exciting the viewer. It is to a certain extent similar to erotica, which is the use of sexually arousing imagery. Over the past few decades, an immense industry for the production and consumption of pornography has grown, due to emergence of the VCR, the DVD, and the Internet, as well as the emergence of social attitudes more tolerant of sexual portrayals. Performers in pornography are referred to as pornographic actors (or actresses), or the more commonly known title, "porn star", and are generally seen as qualitatively different from their non-pornographic counterparts.

Pornography may use any of a variety of media—printed literature, photos, sculpture, drawing, painting, animation, sound recording, film, video, or video game. However, when sexual acts are performed for a live audience, by definition it is not pornography, as the term applies to the depiction of the act, rather than the act itself. Thus, portrayals such as sex shows and striptease are not pornography.

In most countries pornography is treated as a separate entity, both culturally and legally, from depictions of naked persons in art or photography. See "nudity" for more information.

source : http://en.wikipedia.org/wiki/Porn