Pornography or porn is the explicit epiction of sexual subject matter, especially with the sole intention of sexually exciting and entertaining the viewer. It is to a certain extent similar to erotica, which is the use of sexually-arousing imagery for mainly artistic purposes. 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.