Imam
Imam has several meanings, depending on context.
The common everyday use is for a person leading Muslim congregational prayers.
The term is also used for a recognized religious leader or teacher in Islam, often for the founding scholars of the four Sunni madhhabs, or schools of religious jurisprudence (fiqh). For example, Imam Abu Hanifa. Which also leads less partisan Sunnis (that is, less inclined to view of Shias as outside the fold of Islam) to call also refer to at least one of the Shia Imams (see below), Jafar Sadiq, with that title.
In the Shia context (and for some Sunni groups), Imam also has a meaning more central to belief.
According to the Twelve-Imam Shiite dogma, imam refers only to one of twelve early leaders of Islam—Ali, Hasan, Husayn, and nine of Husayn's descendants. See: Shia Imam
The Ismailis trace a different line of Imams, branching at one of Husayn's descendants, Ismail bin Jafar.
The Zayidis trace a different line, branching at Husayn's grandson,
