Prostitutes wear the bow of their sash, or obi, in front of their kimono, but geisha wear their obi at the back. True geisha, who do not engage in paid sexual activity, usually had the luxury of a professional aide to help them in the difficult process of dressing; their clothing is made up of several layers of kimono and undergarments, and an obi is more than a simple band of cloth. Dressing could take over an hour, even with professional help. Prostitutes, however, had to take off their obi several times a day, so theirs were far less complex, and tied at the front for ease of removal and replacement.