Many westerners think Geisha is a prostitute.
They are not ... Geisha (芸者) geiko (芸子), or geigi (芸妓) are traditional Japanese female entertainers who act as hostesses. They dance, play music and play witty games and conversation, traditionally to entertain male customers, but also female customers today.
There used to be a place called 遊郭 (Yūkaku). Yūkaku meant the regions in Japan where brothels recognized by the government were situated. There is no such places in Japan any more.
The oiran (花魁) were considered a type of yūjo (遊女) "woman of pleasure" or prostitute. However, they are distinguished from ordinary yūjo in that they were entertainers, and many became celebrities even outside the pleasure districts. Their art and fashions often set trends and, because of this, cultural aspects of oiran traditions continue to be preserved to this day.