Imam Abu Hanifa (Nu'man bin Thabit) is the founder of the Hanafi school, which is known for its emphasis on Qiyas (analogy) and Ra'y (reasoned opinion).

Ijma represents the consensus of Muslim jurists on a legal matter after the death of the Prophet Muhammad (PBUH).

Imam Malik gave special importance to 'Amal ahl al-Madinah' (the practice of the people of Madinah), considering it a strong evidence of the Sunnah.

Imam al-Shafi'i authored 'Al-Risala', which laid down the formal methodology for Usul al-Fiqh, integrating Quran, Sunnah, Ijma, and Qiyas.

Qiyas is the process by which the laws of the Quran and Sunnah are extended to new cases by comparing them to original cases based on a shared effective cause (illah).

Imam Ahmad bin Hanbal established the Hanbali school, which is recognized for its strict adherence to Hadith and traditional texts.

Ijtihad is the effort of a jurist to derive a ruling from the sources of law in cases where there is no explicit text from the Quran or Hadith.

The Jafari school is the predominant school of jurisprudence for the Twelver Shia branch, named after Imam Jafar al-Sadiq.

Istihsan (juridical preference) allows a jurist to depart from a strict Qiyas in favor of a ruling that better aligns with the overall objectives of Shariah.

Al-Muwatta is the earliest collection of Hadith and Fiqh compiled by Imam Malik bin Anas, which serves as a cornerstone for the Maliki school.

The Maliki school is known for giving significant weight to Maslaha Mursala, which refers to rulings based on public welfare where there is no specific textual evidence.

Qiyas is the process of analogical deduction where the ruling of an original case (Asl) is applied to a new case (Far') due to a shared effective cause (Illah).

Usul al-Fiqh relates to the principles and methodology of derivation, while Furu al-Fiqh refers to the substantive laws (the branches) derived from these principles.

A Fatwa is a formal legal ruling or interpretation given by a Mufti (legal expert) in response to a question or case.

While the Quran, Sunnah, and Ijma are primary/foundational, Urf (custom) is considered a supplementary source that may be valid if it does not contradict the primary texts.

Linguistically, Fiqh means to understand or comprehend deeply; in technical terms, it refers to the science of deriving Islamic laws from their sources.

Fard (or Wajib) denotes acts that are strictly obligatory, and their omission is considered a transgression in Islamic law.

The Zahiri school, founded by Dawud al-Zahiri, argues for the literal meaning of the Quran and Hadith and rejects analogy (Qiyas) if it deviates from the text.

Sadd al-Dhara'i is a legal principle employed to prohibit acts that are outwardly permissible but lead to forbidden or harmful consequences.