A fatwā ( US: ; Arabic: فتوى; plural fatāwā فتاوى) is a legal ruling on a point of Islamic law (sharia) given by a qualified Faqih (Islamic jurist) in response to a question posed by a private individual, judge or government. A jurist issuing fatwas is called a mufti, and the act of issuing fatwas is called iftāʾ. Fatwas have played an important role throughout Islamic history, taking on new forms in the modern era.

Resembling jus respondendi in Roman law and rabbinic responsa, privately issued fatwas historically served to inform Muslim populations about Islam, advise courts on difficult points of Islamic law, and elaborate substantive law. In later times, public and political fatwas were issued to take a stand on doctrinal controversies, legitimize government policies or articulate grievances of the population. During the era of European colonialism, fatwas played a part in mobilizing resistance to foreign domination.

Muftis acted as independent scholars in the classical legal system. Over the centuries, Sunni muftis were gradually incorporated into state bureaucracies, while Shia jurists in Iran progressively asserted an autonomous authority starting from the early modern era.

In the modern era, fatwas have reflected changing economic, social and political circumstances, and addressed concerns arising in varied Muslim communities. The spread of codified state laws and Western-style legal education in the modern Muslim world has displaced muftis from their traditional role of clarifying and elaborating the laws applied in courts. Instead, modern fatwas have increasingly served to advise the general public on other aspects of sharia, particularly questions regarding religious rituals and everyday life. Modern public fatwas have addressed and sometimes sparked controversies in the Muslim world, and some fatwas in recent decades have gained worldwide notoriety. The legal methodology of modern ifta often diverges from pre-modern practice, particularly so in the West. Emergence of modern media and universal education has transformed the traditional institution of ifta in various ways. While the proliferation of contemporary fatwas attests to the importance of Islamic authenticity to many Muslims, little research has been done to determine how much these fatwas affect the beliefs or behavior of the Muslim public.