Rahim Al-Hussaini was named Wednesday as the new Aga Khan, spiritual leader of the world's millions of Ismaili Muslims. The 53-year-old succeeds his father, who died on Tuesday.

Hussaini, son of Prince Karim Al-Hussaini Aga Khan IV, has been named in his father’s will as his successor to lead the Nizari Ismailis, a Shia Muslim denomination. We take a look at this branch of Shia Islam that has 15 million members worldwide.

The Tuesday death of the Aga Khan, the spiritual leader of the world’s millions of Ismaili Muslims, and the Wednesday announcement of his successor struck a deep chord with Houston’s sizable Ismaili Muslim community.