A call girl or escort is a sex worker who (unlike a street walker) is not visible to the general public. Nor does she usually belong to an institution like a brothel. One must summon her, usually by calling a telephone number—hence the name call girl. Often, call girls advertise their services in small ads in magazines, and more recently through the internet, although an intermediary advertiser such as an escort agency may be involved in promoting higher class escorts. The lower class side of escorts may be handled by a pimp or a pander.
Call girls are commonly perceived to be elite amongst prostitutes, far more skilled, able to pick and choose amongst their potential clients and therefore demand higher prices for their services, and are more attractive, educated, well-groomed and youthful than street prostitutes. An escort service will not take on any woman that is unattractive, has a visible drug problem (such as needle marks from injecting drugs), or who presents an overly negative personality. Escort services seek to establish a reputation for offering desirable women and know that their customers only give them one chance. If an escort service sends an undesirable woman to a client, the client will very likely not use that service again. Also, many escort agencies do criminal background checks on applicants to weed out those that have been arrested for street prostitution or other types of crimes. This weeding out is done to reduce the chances of being accused of procuring prostitution, trying not to draw the attention of law enforcement agencies. For these reasons, there is rarely any cross-over between call girls and street prostitutes.