The term 'member of Islam's second-largest branch' can be summarized as a Shiite, which is a six-letter word. Shiites are members of the second-largest branch of Islam, after Sunnis. Shiites believe that only descendants of the Prophet Muhammad's family should lead the Islamic community, while Sunnis believe that any qualified Muslim can lead. Shiites make up about 10-15% of the world's Muslim population.