The Shia branch of Islam is one of the two main sects, the other being Sunni. Shia Muslims believe that leadership should have remained within the family of the Prophet Muhammad, specifically through his cousin and son-in-law, Ali. This belief leads to a distinct interpretation of Islamic teachings and practices. Shia Islam is characterized by its emphasis on the role of Imams, who are considered spiritual leaders and guides. The largest Shia group is the Twelvers, who believe in a line of twelve Imams, with the last one, Muhammad al-Mahdi, believed to be in occultation and will return as a messianic figure.