A traditional Japanese courtesan in Edo (present-day Tokyo), the Yoshiwara. They were a much higher-class subtype of yuujo, the iconic feudal-era Japanese prostitutes.
Unlike yuujo, oiran were more educated and cultured, and had talents beyond those used in the bedroom. This gave them a social standing which put them well above any common prostitute, even outside the red-light districts. The companionship of an oiran did not come cheaply, so their clientele were primarily men of high political or social ranking.
Oiran should not be confused with geisha, who tend to dress far less luxuriously and who do not provide any sexual services. After World War II, the geisha eventually ended up replacing the role of "classic, respectable female entertainer" that oiran had filled in Japanese society.