A Women's Guide to the Laws of Niddah (Artscroll Halachah Series);

Traditional Judaism considers the hair of a married woman erotic. As a result, married Jewish women are generally expected to cover their hair, except in front of her husbands, and sometimes in the company of other women. For most of Jewish history this practice was not disputed - mainly because society at large also considered it immodest for women to let their hair down in its city streets. However, as the general definition of modesty has changed in the last two centuries, Jewish women have followed suit, debating the necessity of covering their hair in a world that remains 'uncovered.' Today, most observant, married Jewish women cover their hair in some way although a vocal minority declines to do so at all. Hair covering has, therefore, become the bellwether for religiosity, turning practice into politics. Sources dispute the when, why, and how of hair covering,