A guide to Muslim diversity
'The Twelvers believe that the descendants of Prophet Muhammad (PBUH)–through Imam Ali, his son-in-law, his sons, and then Hussain’s descendants– are the best source of knowledge about the Qur’an and Islam, and therefore the most trusted carriers and protectors of the Prophet’s (PBUH) traditions.’
The history outlined above, however, has led to the development of parallel forms of leadership among Muslims: formal leadership which might be described in today’s language as institutional leadership manifest in the Caliphate, and the informal religiously-based leadership personified at the time by individual leaders. This form of leadership begins in what is today referred to as the Twelvers. The ‘Twelvers’ primarily refers to leaders in the Shia tradition, but is mentioned by other traditions as well. This is based on their devotion to Imam Ali and derived from their belief in divinely ordained leaders – known as the Twelve Imams.

The Twelvers believe that the descendants of Prophet Muhammad (PBUH) – through Imam Alī, his son-in-law, his sons, and then Hussain’s descendants – are the best source of knowledge about the Qur'an and Islam, and therefore the most trusted carriers and protectors of the Prophet’s (PBUH) traditions. The vast majority of Shias recognise the religious authority of these Twelve Imams (as do many of the groups which have evolved from Shiism), who were considered to be the spiritual and political successors to Prophet Muhammad (PBUH). The vast majority of the Shia community are Twelvers, but often the Shia are referred to as Twelvers by default, which is not correct.

Shia – The Twelvers