Prostitution is a type of sex work that involves engaging in sexual activity in exchange for payment. The definition of "sexual activity" varies, and is often defined as an activity requiring physical contact (e.g., sexual intercourse, non-penetrative sex, manual sex, oral sex, etc.) with the customer. The requirement of physical contact also creates the risk of transferring infections. Prostitution is sometimes described as sexual services, commercial sex or, colloquially, hooking. It is sometimes referred to euphemistically as "the world's oldest profession" in the English-speaking world. A person who works in the field is usually called a prostitute or sex worker, but other words, such as hooker and whore, are sometimes used pejoratively to refer to those who work in prostitution. The majority of prostitutes are female and have male clients.
Prostitution occurs in a variety of forms, and its legal status varies from country to country (sometimes from region to region within a given country). In most cases, it can be either an enforced crime, an unenforced crime, a decriminalized activity, a legal but unregulated activity, or a regulated profession. It is one branch of the sex industry, along with pornography, stripping, and erotic dancing. Brothels are establishments specifically dedicated to prostitution. In escort prostitution, the act may take place at the client's residence or hotel room (referred to as out-call), or at the escort's residence or a hotel room rented for the occasion by the escort (in-call). Another form is street prostitution.
According to a 2011 report by Fondation Scelles there are about 42 million prostitutes in the world, living all over the world (though most of Central Asia, the Middle East and Africa lack data, studied countries in that large region rank as top sex tourism destinations). Estimates place the annual revenue generated by prostitution worldwide to be over $100 billion.
The position of prostitution and the law varies widely worldwide, reflecting differing opinions. Some view prostitution as a form of exploitation of or violence against women, and children, that helps to create a supply of victims for human trafficking. Some critics of prostitution as an institution are supporters of the "Nordic model" that decriminalizes the act of selling sex and makes the purchase of sex illegal. This approach has also been adopted by Canada, Iceland, Ireland, Northern Ireland, Norway, France and Sweden. Others view sex work as a legitimate occupation, whereby a person trades or exchanges sexual acts for money. Amnesty International is one of the notable groups calling for the decriminalization of prostitution.