The primary sources of knowledge about Islam are the Qur’an, which adherent Muslims believe is the divinely revealed word of God, and the Sunnah, which refers to the example or precedent of the Prophet Muhammad (i.e., what he said, did, approved, disapproved, caused, ordered, or allowed to happen). Much of what is known about the Sunnah is from the collection of sayings or reports known as Hadith, or prophetic tradition. The Hadith describe actions of the Prophet Muhammad or actions that his companions attributed to his teachings. Hadith also elaborate on and provide context to the Qur’an.
Though both Sunnis and Shi’as revere and respect the descendants of the Prophet Muhammad, many Shi’a’s consider the rulings of the twelve Imams a primary source having a status similar to that of the aforementioned sources. Other sources may exist for different Muslim sects.
In addition to these primary sources, Muslims have also traditionally relied on the following additional sources: scholarly consensus: that is, the agreement of knowledgeable scholars upon a particular issue; and analogical reasoning: that is, the application of principles or laws derived from the Qur’an and Sunnah to similar situations not explicitly addressed by them. The lived experience of Islam, which naturally varies widely not only in different cultures but also between different individuals, also impacts and determines a Muslim’s understanding and practice of Islam.