In its most common usage, the term harem refers to the section of a house where a Muslim leader's wives live. More broadly, a harem serves as the quarters restricted to female members of a family. The term also refers to the women themselves. The purpose of a harem is to protect women from inappropriate contact with men. Closely linked with the term haram, meaning forbidden, the word conveys a sense of sacredness and inviolability. Only husbands and relatives may enter this part of the home.

Harems existed in the Middle East long before the rise of Islam. Pre-Islamic rulers in Egypt, Persia, and Assyria often had large harems in their royal courts. These consisted of wives, concubines, female attendants, and other attendants who served as court officials. Rulers added wives from prestigious and influential families to their harems to forge political alliances. Some of these women played public roles. Others jockeyed for position from within the harem to gain power for themselves or their sons. Internal struggles within a harem had major political consequences, sometimes leading to the downfall of a dynasty.

As the new Muslim community conquered these older societies, the new rulers adopted the concept of harem. This was justified by parts of the Qur'an requiring actions that ensure modesty and chastity. Muslims and Arabs of all classes kept harems. In homes of the wealthy, wives had their own servants and suites of rooms. Families of average income also placed their women in seclusion. Even poorer households maintained separate, though more cramped, quarters for women.

Among the nobility, the practice of enclosing women in a harem served as a sign of status, showing that the family did not need its women to work for a living. Poorer women often had no choice but to earn money in the fields, as clerical workers, or as domestic servants. In Islamic countries, female workers wore veils in order to separate themselves symbolically from the world of men.

In the twentieth century, the harem system declined in popularity. Polygyny became less common as women became more educated and joined the workforce as professionals. Some conservative Muslims continue the practice of maintaining harems, however, and radical groups in such places as Saudi Arabia call for a return to the seclusion of wives and daughters and an end to employment for women outside the home.