A fatwa is a legal ruling on a point of Islamic law given by a qualified Faqih (Islamic jurist) in response to a question posed by a private individual, judge, or government. The word "fatwa" comes from the Arabic root f-t-w, which means "youth, newness, clarification, explanation". A jurist issuing fatwas is called a mufti, and the person who asks for a fatwa is known as mustafti. The act of issuing fatwas is called iftāʾ. Fatwas are usually issued in response to questions from individuals or Islamic courts. They can range from a simple yes/no answer to a book-length treatise. A short fatwa may state a well-known point of law in response to a question from a lay person, while a "major" fatwa may give a judgment on an unprecedented case, detailing the legal reasoning behind the decision. Fatwas encompass every aspect of life, such as creed, acts of worship, transactions, the economy, family, politics, governance, arbitration, etc..

Fatwas are not considered binding judgments, and a requester who finds a fatwa unconvincing is permitted to seek another opinion. While fatwas often begin with a request by a Muslim layperson, they may be issued in response to a given situation. Fatwas related to acts of worship include all rules of the obligatory, prohibited, recommended, disliked, and permissible fatwas. Long fatwas are research-based and clarify the ruling and cite the opinions of different scholars and evidence on which they base their opinions. The fatwas then mention the preponderant ruling from among the different rulings cited along with proof.

It is important to note that a fatwa rarely calls for death, and it can be issued by a variety of religious authorities. The collective fatwa, sometimes called ijtihād jamāʿī, is a new historical development, and it is found in such settings as boards of Islamic financial institutions and international fatwa councils.