From Arabic, lit. Sign of God; a title used by the Imami Twelver Shi‘is. The rank of Ayatollah is believed to have been established in the Safawid period (1501-1722 CE). The Ayatollah usually heads the hierarchy amongst the Twelver Shi‘i mujtahids. The holder of the title in today’s Islamic Republic of Iran has two main roles: on the administrative level, the Ayatollah regulates religious dues (taxes) and heads various centres of learning; on the intellectual and spiritual levels, he is considered as a primary source for religious learning.