The Shia tradition is one of the two main branches of Islam, the other being Sunni. It originated from a disagreement over the rightful successor to the Prophet Muhammad after his death in 632 CE. Shia Muslims believe that leadership should have remained within the Prophet's family, specifically with his cousin and son-in-law, Ali. Shia practices include unique rituals and beliefs, such as the commemoration of Ashura, which marks the martyrdom of Imam Hussein, the grandson of the Prophet. Shia communities often emphasize the importance of Imams, who are considered spiritual leaders and guides, believed to be divinely appointed and infallible.