Jafari alternatively Jafaryia is the largest Shia school of thought, predominant in Iran, also known as the "Ithna Asharia" meaning "the Twelvers". Jafari is taken to refer to "the Twelvers" to the exclusion of the Ismailis ("the Seveners") and the Zaidis ("the Fivers").
The Jafari school of thought (madhab) and deduction of jurispudence (fiqh) was founded by the 6th Shia Imam Jafar Sadiq. The founders of the Sunni Hanafi and Maliki schools of thought were students under Imam Jafar Sadiq.
The Jafari derive their Sharia, or religious law, from the Quran and the Sunnah similar to the Sunni schools of thought (madhab) Hanafi, Maliki, Shafai and Hanbali. The difference in Sunni and Shia Sharia results from;
(1) Alternate interpretations of the Quran,
(2) Alternate interpretation of the Hadith from which the Sunnah is derived,
(3) Disagreement on the veracity of several Hadith,
(4) The Shia non-acceptance of the "examples" and verdicts of the three first Caliphs, Abu Bakr, Omar and Uthman,
(5) the concept of the Infallibility (masuum) of the Twelve Imams, or the Fourteen Infallibles (including Muhammad and his daughter Fatima Zahra), hence the Shia accept their examples and verdicts as is, if they can be proven to have been authentically related from any of them.