A call girl is a prostitute who is not visible to the general public, like a street walker, and does not commonly belong to an institution like a brothel. One must summon her, usually by calling a telephone number, although an intermediary such as a pimp or a pander may be involved. By this act of calling the term call girl was derived.

Call girls are commonly perceived to be of the highest social standing amongst prostitutes, far more skilled, able to pick and choose amongst their potential clients and therefore demand higher prices for their favors. In practice, a call girl may be the same woman whom the customer or john saw soliciting on a street corner only moments before.