The largest of the three major branches of Islam Sunni, Shia, and Sufi comprising approximately 90 percent of the world’s Muslims. Sunni is the mainstream form of Islam, according to its adherents, who Sunni Iraqi girls at prayer in Baghdad, August 2003. Sunni Islam is practiced by 90 percent of the world’s Muslims. Â© LYNSEY ADDARIO/CORBIS number up to 1 billion worldwide. It is the majority approach to the faith in all mostly Islamic nations except for Iraq and Iran and also in Europe, Australia, North America, and other nations where Islam is a minority religion. Although it is the mainstream form of the faith, Sunni Islam is not an established, firm, orthodoxy. Instead, it provides room for a variety of interpretations and approaches. Several interrelated features of Sunni Islam mark it out from other branches of the faith. One is a declared loyalty to the sunna, a term referring to Islamic customs or accepted codes of belief and practice as introduced in the Hadith and other Islamic traditions apart from the Qur’an. The best examples of sunna in practice were set by Muhammad and the companions of the Prophet during the seventh-century decades of Islam’s origins. Sunni Muslims use the term sunnat al-nabi, which means example of the Prophet, as a guide in their daily lives. Taken as a whole, the sunna forms an authoritative, living commentary on the ultimate authority, the Qur’an. The word Sunni is simply a shortened form of Ahl al-Sunna w’l-jama’a, or the people of the Sunna. For many believers, conformity to the sunna amounts to living as a devout Muslim and assures entrance into the Islamic heaven after death. Sunni Flexibility In specific regions Sunna is generally formed by the consensus of a community, provided that consensus is based in the Qur’an, Hadith, and other traditions. It is therefore broad enough to make acceptable a reasonably wide range of Islamic practices, and another important feature of Sunni Islam is its readiness to incorporate a variety of different ethnic and linguistic traditions into the global community of Islam. The Sunni approach accepts that varied practices will occur when Islam comes into contact with existing social and cultural traditions. Thus, Islam in practice is not expected to be exactly the same in Saudi Arabia and Indonesia. On the issue of women in Islam, for example, both cultural traditions and a strict interpretation of the sunna encourage women to wear the veil in Saudi Arabia. In Indonesia, by contrast, women traditionally held greater social freedoms and responsibilities prior to the arrival of Islam and the sunna is interpreted more broadly, resulting in women commonly wearing a hijab (the traditional black gown) but leaving their faces uncovered. Neither approach is necessarily orthodox, and both are acceptable. This same openness of interpretation applies to many other issues as well, and is likely a major aspect of Sunni Islam’s appeal and success around the world. The notion of community consensus as the authority for local practice is an echo of the historical evolution of Sunni Islam. Sunnism emerged as a result of the larger attempt to create a kind of orthodox, or mainstream, Islam in the centuries following the death of the Prophet. The effort was partly a reaction to the rise of different branches of the faith that elders and scholars did not entirely approve of or see as true to the teachings of Muhammad and his companions. Most notably among these was Shia Islam, but as the religion spread rapidly in the seventh and eighth centuries, many local communities had vastly different understandings of the teachings of the Prophet, and in some places teachings were simply made up. Moreover, as Islam moved beyond Arabia, leaders found that some of these teachings were not entirely appropriate or applicable. Islamic scholars responded to these challenges by creating set lines of religious authority or bases for interpretation. Among them was al-Shafi’i (767820), a legal scholar living in Cairo, Egypt, who was a distant descendant of the Prophet. AlShafi’i established that the sunna was formed by the lives, words, and deeds of Muhammad and his companions and that only the Qur’an itself had greater authority. Different Interpretations of the Successors to the Prophet Other prominent Islamic scholars added to al-Shafi’i’s contributions over the next centuries, thus giving greater weight to the sunna. They developed such methods as tafsir, which was a kind of study of interpretation of the Qur’an and Hadith. By the tenth century, a systematic tafsir had evolved that worked through the Qur’an verse by verse and explained many of the implications of the text when they were not apparent. This effort was partly due to tendency among some Muslims to interpret the Qur’an and Hadith according to personal speculation or intuition, or alternatively to add to these sources stories from other religious traditions or from folklore. Another important development was the rise of four accepted schools of legal interpretation in order to allow for some flexibility in understanding sharia or Islamic law. These were the Shafite (based on al-Shafi’i’s teachings), the Hanifite, the Malikite, and the Hanbalite. The early culmination of all these teachings came with the work of the scholar al-Tabari (839 923), whose Qur’an Commentary remains a basic source for the interpretation of sunna and represented the consensus of Islamic scholars during these formative centuries. A clear differentiation between Sunni and Shia Islam, and a reflection of its relative openness, appears in the two branches’ understanding of the origins of the caliphs, or successors to the Prophet. Sunni Muslims accept the first three caliphs, Abu Bakr, Omar, and Uthman, as legitimate caliphs even though they were not relatives of Muhammad. Shia Muslims only accept the line of caliphs beginning with the fourth, Ali, who was Muhammad’s cousin and son-in-law. The basis of these different interpretations was the Sunni belief that the caliph was an earthly ruler only, since no figure after Muhammad could be anything other than human. Shia Muslims argue, by contrast, that true caliphs must be divinely ordained. Meanwhile, and in accordance with the general principles of sunna, Sunni Muslims also acknowledge that the caliphate had to reflect political reality and that there needed to be some flexibility in the selection of these figures. Ostensibly, Sunni Muslims hold that caliphs must be members of the Quraysh tribe that Muhammad belonged to. But historically they have also accepted members of leading families of Mecca and even, after the Turks replaced the Arabs as the dominant powers in the Islamic heartland of the middle east, the Turkish sultans of the Ottoman Empire. SEE ALSO: Islam; sharia; Shia IslamDo Sunni Muslims think it’s right to kill Shi’a Muslims? – Quora .