The title of the imam or leader of the Nizari sect of Ismaili Muslims. The first Aga Khan was given his title in 1818 by the shah of Persia, subsequently moving with the majority of the Nizaris to the Indian subcontinent. The present (4th) Aga Khan (Karim Al‐Hussain Shah; 1936– ) inherited the title from his grandfather in 1957. The title of Aga Khan (which comes from the Turkish words for master and ruler) carries with it responsibility for various services and welfare provisions for members of the Nizari community.