Ayatollah is an honorific title for high-ranking Twelver Shia clergy in Iran that came into widespread usage in the 20th century.
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Twelver Shīʿism, also known as Imāmiyya, is the largest branch of Shīʿa Islam, comprising about 85 percent of all Shīʿa Muslims. The term Twelver refers to its adherents' belief in twelve divinely ordained leaders, known as the Twelve Imams, and their belief that the last Imam, Imam al-Mahdi, lives in Occultation and will reappear as the promised Mahdi.
18th century mirror writing in Ottoman calligraphy. Depicts the phrase 'Ali is the vicegerent of God' in both directions.
Imam Husayn Shrine in Karbala, Iraq, where the Battle of Karbala took place