Islam is a major world religion that is based on the teachings of the prophet Muhammad. It is divided into two main branches, Sunni and Shia. Sunni Islam is the largest branch of Islam, with over 1 billion adherents worldwide. It is based on the teachings of the Quran and the Sunnah, which are the sayings and actions of the Prophet Muhammad. Shia Islam is the second-largest branch of Islam, with around 200 million adherents. It is based on the teachings of the Quran and the Hadith, which are the sayings and actions of the Prophet Muhammad's family and companions. Both branches of Islam share the same core beliefs, but differ in their interpretation of certain aspects of Islamic law.