The Ismaili family divided twice more, and the resulting communities are governed in quite different ways.
The first split, in 1094, was over the Fatimid succession and produced the Nizari and Mustali lines. The Nizaris follow a living, present Imam in unbroken descent; the office is held today by the Aga Khan, whose guidance on matters of faith and daily life is binding on the community. The Mustalis hold that their Imam went into concealment in 1132 and is represented by a chief missionary, the dai al-mutlaq; the largest Mustali community is the Dawoodi Bohras of western India and Pakistan, led from Mumbai.
Nizari governance under the Aga Khan is genuinely unusual among religious institutions. It runs through a written constitution promulgated for the whole community, national and regional councils, and the Aga Khan Development Network, one of the largest private development agencies in the world, operating hospitals, universities, microfinance, rural support and architectural conservation across Asia and Africa and serving populations regardless of faith. The community is small, estimates generally run to a few million, though no reliable global census exists, and is disproportionately educated, urban and prosperous, with large diasporas in Canada, Britain and East Africa.
A third community, the Druze, emerged from Fatimid Ismailism in the eleventh century around the figure of the caliph al-Hakim and developed into a separate faith that no longer identifies as Ismaili or, in the view of most Muslims and of many Druze, as Muslim; it accepts no converts and reserves its scriptures to an initiated minority.
Practice among Nizaris departs visibly from Muslim norms, congregational prayer in a jamatkhana rather than a mosque, and a distinctive observance of Ramadan, which is part of why other Muslims have often disputed their standing.