(Arabic: “People of the Book”), in Islāmic thought, those religionists such as Jews, Christians, and Zoroastrians who are possessors of divine books (i.e., the Torah, the Gospel, and the Avesta), as distinguished from those whose religions are not based on divine revelations. The latter are an imprecisely identified group referred to as Sabaeans but also considered “People of the Book.”

The Prophet Muḥammad gave many privileges to Ahl al-Kitāb that are not to be extended to heathens. Ahl al-Kitāb are granted freedom of worship; thus, during the early Muslim conquests, Jews and Christians were not forced to convert to Islām and had only to pay a special tax for their exemption from military service. Muslim authorities are responsible for the protection and well-being of Ahl al-Kitāb, for, according to a saying of the Prophet, “he who wrongs a Jew or a Christian will have myself 【the Prophet】 as his indicter on the day of judgment.” After Muḥammad's death, his successors sent strict instructions to their generals and provincial governors not to interfere with Ahl al-Kitāb in their worship and to treat them with full respect.

Muslim men are permitted to marry women from Ahl al-Kitāb even if the latter choose to remain in their religion; Muslim women, however, are not allowed to marry Christians or Jews unless they convert to Islām.