A pornographic film actor or actress, adult entertainer, or porn star is a person who performs sex acts in video that is usually characterized as a pornographic movie. Such videos tend to be made in a number of distinct pornographic subgenres and attempt to present a sexual fantasy and the actors selected for a particular role are primarily selected on their ability to create or fit that fantasy. Pornographic videos are characterised as either "softcore", which does not contain depictions of sexual penetration or "extreme fetishism" and "hardcore", which can contain depictions of penetration or extreme fetishism, or both. The genres and sexual intensity of videos is mainly determined by demand. Depending on the genre of the film, the on-screen appearance, age, and physical features of the main actors and their ability to create the sexual mood of the video is of critical importance. Most actors specialize in certain genres, such as gay sex, lesbian sex, bondage, strap-on sex, anal sex, double penetration, semen swallowing, teenage women, interracial or MILFs.