It is an ancient tradition in the hot eastern countries and is an important hygienic measure. The reason being, despite thorough bathing, it is difficult to remain odor free and, at the same time, protect skin from irritation in a hot climate unless body hair is removed. Depilatory powder or razor blades are sold from kiosks either just outside or inside every hammam. While the powder no longer contains harsh agents like sulphurous arsenic, it removes body hair in a few minutes after it is mixed with water to form a paste and applied. I never met a foreigner in Istanbul who underwent the process, but a few weeks later, in Bursa, it was a different story.
Islamic faith prohibits men and women from bathing together.
Either there are separate baths or men and women take turns in the same hammam. When the bath has been appropriated by women, a napkin, or a piece of drapery hung over the entrance gives notice. Because hammams are not coed, I had no way of knowing whether women's bathing differed from men's. So, in Bursa, I met two French women, willing to dedicate a couple of hours to my sweat-bath research. Afterwards, we met outside.