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 film is of critical importance.
Most actors specialize in certain genres, such as lesbian sex, bondage, strap-on sex, anal sex, double penetration, semen swallowing, teenage women, interracial or MILFs.
Pornographic films are characterized 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 films is mainly determined by demand.
The pornography industry in the United States was the first to develop its own movie star system, especially for commercial reasons.