A madhhab, also spelled as mazhab, is a school of thought within fiqh, which is the Islamic jurisprudence. The major Sunni madhhabs are Hanafi, Maliki, Shafii, and Hanbali, which emerged in the ninth and tenth centuries CE. These schools recognize each others validity and have interacted in legal debate over the centuries. The development of Shia legal schools occurred along the lines of theological differences and resulted in the formation of the Jafari madhab amongst Twelver Shias, as well as the Ismaili and Zaidi madhhabs amongst Ismailis and Zaidis respectively. The Ibadi legal school, distinct from Sunni and Shia madhhabs, is predominant in Oman. Unlike Sunnis, Shias, and Ibadis, non-denominational Muslims are not affiliated with any madhhab.

The purpose of a madhhab is to provide scholars with a methodology for understanding the sources of Islamic law. The various madhhabs use the Quran, Sunnah, consensus (Ijmaa), and analogy in establishing a ruling. The rulings of these schools are followed across the Muslim world without exclusive regional restrictions, but they each came to dominate in different parts of the world.

It is not obligatory for a Muslim to follow any particular madhhab among the four madhhabs. People vary in their level of understanding and should follow the truth and what is correct, regardless of who says it. The four madhhabs are named after the four imams – Imam Abu Hanifah, Imam Malik, Imam al-Shafii, and Imam Ahmad. These imams learned fiqh from the Quran and Sunnah, and they are mujtahidin in this regard. The mujtahid either gets it right, in which case he will have two rewards, the reward for his ijtihad and the reward for getting it right, or he will get it wrong, in which case he will be rewarded for his ijtihad and will be forgiven for his mistake. None of them called people to follow his madhhab, or was partisan in following it, or obliged anyone else to act in accordance with it or with a specific madhhab. Rather they used to call people to follow the Quran and Sunnah, and they would comment on the texts of Islam, and explain its basic principles and discuss minor issues according to general guidelines, and issue fatwas concerning what people asked about, without obliging any of their students or anyone else to follow their views.