Commercial sex is a major industry in the United States and increasingly around the world. Two prominent aspects of it are prostitution and pornography.

Commercial sex workers engage in partnered sexual activity in return for payment, such as money, gifts, or drugs. There are several venues in which they work in the United States, including their own homes, in-call services, out-call services, and massage parlors. The working conditions, risks, and income of a sex worker depend on the setting. Third parties who may be involved include a pimp, madam, or manager; the involvement of these people generally limits a worker's autonomy. Sex trafficking involves exploitation and is a major problem.

Research suggests that a sex worker's well-being depends upon the risk level of the setting in which she works, the reasons she entered sex work, and whether she experienced victimization as a child or adolescent.

Data indicate that the use of prostitutes has declined substantially in the United States in the past 50 years. About one-half of the clients of female workers are occasional johns; the other 50 percent are repeat clients. Some men rely on sex workers for their sexual outlet.

Some male sex workers serve a female clientele. They may work as escorts, employees of massage parlors, or gigolos. Hustlers cater to a male homosexual clientele.

Distinctions are made among pornography (sexually arousing art, literature, or film), obscenity (material offensive to authorities or society), and erotica (sexual material that shows men and women in equal, humane relationships). Pornographic magazines, films, and videocassettes, both soft core (erotica) and hard core, are a multibillion-dollar business. Computer porn has mushroomed in the past 20 years; people can discuss explicit sexual activity online, read sexually arousing stories, download sexually explicit images, or purchase a variety of goods and services at adult Web sites. Children, often runaways, are the star victims in kiddie porn.

Some feminists object to pornography on the grounds that it debases women, encourages violence against women, and portrays unequal relationships between men and women.

Social-psychological research indicates that exposure to portrayals that the viewer finds acceptable is arousing to both men and women. Men are more likely to report arousal than women. Massive exposure leads to more favorable attitudes toward the behavior observed. Some studies find that exposure to violent pornography creates more tolerant attitudes toward violence against women, but others find no such effect. Exposure to portrayals of consenting heterosexual activity leads to an increase in sexual thoughts and behavior. Exposure to portrayals of sexual or nonsexual violence toward women increases men's aggression against women. Education about the effects of pornography is probably the best solution to the problems created by pornography.