Sunni Islam ( /ˈsuːni/ or /ˈsʊni/ ) is the largest denomination of Islam . Its name comes from the word Sunnah , referring to the exemplary behaviour of the Islamic prophet Muhammad .  The differences between Sunni and Shia Muslims arose from a disagreement over the choice of Muhammad's successor and subsequently acquired broader political significance, as well as theological and juridical dimensions.
According to Sunni traditions, Muhammad did not clearly designate a successor and the Muslim community acted according to his sunnah in electing his father-in-law Abu Bakr as the first caliph . This contrasts with the Shi'a view, which holds that Muhammad intended his son-in-law and cousin Ali ibn Abi Talib to succeed him. Unlike the first three ( Rashidun ) caliphs, Ali was from the same clan as Muhammad, Banu Hashim , and Shia Muslims consider him legitimate by favour of his blood ties to Muhammad.  Political tensions between Sunnis and Shias continued with varying intensity throughout Islamic history and they have been exacerbated in recent times by ethnic conflicts and the rise of Wahhabism .
As of 2009, Sunni Muslims constituted 87–90% of the world's Muslim population.  Sunni Islam is the world's largest religious denomination, followed by Catholicism . Its adherents are referred to in Arabic as ahl as-sunnah wa l-jamāʻah ("the people of the sunnah and the community") or ahl as-sunnah for short.   In English, its doctrines and practices are sometimes called Sunnism ,  while adherents are known as Sunni Muslims, Sunnis, Sunnites and Ahlus Sunnah. Sunni Islam is sometimes referred to as "orthodox Islam".    However, other scholars of Islam, such as John Burton believe that there's no such thing as "orthodox Islam". 
The Quran , together with hadith (especially those collected in Kutub al-Sittah ) and binding juristic consensus form the basis of all traditional jurisprudence within Sunni Islam. Sharia rulings are derived from these basic sources, in conjunction with analogical reasoning , consideration of public welfare and juristic discretion , using the principles of jurisprudence developed by the traditional legal schools .
In matters of creed , the Sunni tradition upholds the six pillars of iman (faith) and comprises the Ash'ari and Maturidi schools of rationalistic theology as well as the textualist school known as traditionalist theology .
Sunnī ( Classical Arabic : سُنِّي /ˈsunniː/ ), also commonly referred to as Sunnīism , is a term derived from sunnah ( سُنَّة /ˈsunna/ , plural سُنَن sunan /ˈsunan/ ) meaning " habit ", "usual practice",  "custom", "tradition". The Muslim use of this term refers to the sayings and living habits of the prophet Muhammad. In Arabic, this branch of Islam is referred to as ahl as-sunnah wa l-jamāʻah ( Arabic : أهل السنة والجماعة ), "the people of the sunnah and the community", which is commonly shortened to ahl as-sunnah (Arabic أهل السنة).  
One common mistake is to assume that Sunni Islam represents a normative Islam that emerged during the period after Muhammad's death, and that Sufism and Shi'ism developed out of Sunni Islam.  This perception is partly due to the reliance on highly ideological sources that have been accepted as reliable historical works, and also because the vast majority of the population is Sunni. Both Sunnism and Shiaism are the end products of several centuries of competition between ideologies. Both sects used each other to further cement their own identities and doctrines. 
The first four caliphs are known among Sunnis as the Rashidun or "Rightly-Guided Ones". Sunni recognition includes the aforementioned Abu Bakr as the first, Umar who established the Islamic calendar as the second, Uthman as the third, and Ali as the fourth.  The sequence of events of the 20th century has led to resentment in some quarters of the Sunni community due to the loss of pre-eminence in several previously Sunni-dominated regions such as the Levant, Mesopotamia, the Balkans and the Caucasus. 
Sunnis believe that the companions of Muhammad were the best of Muslims. This belief is based upon prophetic traditions such as one narrated by Abdullah, son of Masud , in which Muhammad said: "The best of the people are my generation, then those who come after them, then those who come after them." Support for this view is also found in the Quran , according to Sunnis.  Sunnis also believe that the companions were true believers since it was the companions who were given the task of compiling the Quran . Furthermore, narrations that were narrated by the companions (ahadith) are considered by Sunnis to be a second source of knowledge of the Muslim faith. A study conducted by the Pew Research Center in 2010 and released January 2011  found that there are 1.62 billion Muslims around the world, and it is estimated over 85–90% are Sunni. 
Sunni Islam does not have a formal hierarchy. Leaders are informal, and gain influence through study to become a scholar of Islamic law, called sharia . According to the Islamic Center of Columbia , South Carolina , anyone with the intelligence and the will can become an Islamic scholar. During Midday Mosque services on Fridays, the congregation will choose a well-educated person to lead the service, known as a Khateeb (one who speaks). 
Schools of law
There are many intellectual traditions within the field of Islamic law , often referred to as legal schools . These varied traditions reflect differing viewpoints on some laws and obligations within Islamic law. While one school may see a certain act as a religious obligation, another may see the same act as optional. These schools aren't regarded as sects; rather, they represent differing viewpoints on issues that are not considered the core of Islamic belief.
Historians have differed regarding the exact delineation of the schools based on the underlying principles they follow. Many traditional scholars saw Sunni Islam in two groups: Ahl al-Ra'i, or "people of reason," due to their emphasis on scholarly judgment and discourse; and Ahl al-Hadith , or "people of traditions," due to their emphasis on restricting juristic thought to only what is found in scripture.  Ibn Khaldun defined the Sunni schools as three: the Hanafi school representing reason, the Ẓāhirīte school representing tradition, and a broader, middle school encompassing the Shafi'ite , Malikite and Hanbalite schools. 
During the Middle Ages , the Mamluk Sultanate in Egypt delineated the acceptable Sunni schools as only Hanafi, Maliki, Shafi'i and Hanbali, excluding the Ẓāhirī school.  The Ottoman Empire later reaffirmed the official status of four schools as a reaction to the Shiite character of their ideological and political archrival, the Persian Safavids , though former Prime Minister of Sudan Al-Sadiq al-Mahdi , as well as the Amman Message issued by King Abdullah II of Jordan , recognize the Ẓāhirī and keep the number of Sunni schools at five. 
Differences in the schools
Interpreting Islamic law by deriving specific rulings – such as how to pray – is commonly known as Islamic jurisprudence . The schools of law all have their own particular tradition of interpreting this jurisprudence. As these schools represent clearly spelled out methodologies for interpreting Islamic law, there has been little change in the methodology with regard to each school. While conflict between the schools was often violent in the past, today the schools recognize one another as viable legal methods rather than sources of error or heresy in contrast to one another. Each school has its evidences, and differences of opinion are generally respected.
Pillars of iman
All the branches of Sunni Islam testify to six principal articles of faith known as the six pillars of iman (Arabic for "faith"),  which are believed to be essential for salvation. These are:
- Belief in the One God (see Tawhid )
- Belief in the existence of angels
- Belief in the existence of prophets
- Belief in God's revelations, including the Torah (revealed to Moses ), the Psalms (revealed to David ), the Gospel (revealed to Jesus ), and the Quran (revealed to Muhammad)
- Belief in the Day of Judgment
- Belief in God's predestination
These six articles are what all present-day Sunnis agree on, from those who adhere to traditional Sunnism to those who adhere to latter-day movements. Additionally, classical Sunni Islam also outlined numerous other cardinal doctrines from the eighth-century onwards in the form of organized creeds such as the Creed of Tahawi , in order to codify what constituted "Sunni orthodoxy." While none of these creeds gained the importance attributed to the Nicene Creed in Christianity , primarily because ecumenical councils never happened in Islam, the beliefs outlined in these creeds became the "orthodox" doctrine by ijma , or binding consensus. But while most of the tenets outlined in the classical creeds are accepted by all Sunnis, some of these doctrines have been rejected by the aforementioned movements as lacking strictly scriptural precedent. Traditionally, these other important Sunni articles of faith have included the following (those that are controversial today because of their rejection by such groups shall be denoted by an asterisk):
- Belief in the six principal articles of faith being essential for salvation for Muslims
- Belief in God having created creation with His wisdom
- Belief in Muhammad having been the Seal of the Prophets or the last prophet sent to mankind
- Belief in the Quran being the eternal, uncreated Word of God
- Belief in the beatific vision being a reality in the afterlife, even if it will not be all-encompassing and the "manner" of it remains unknown
- Belief in the Night Journey of Muhammad having happened in a bodily form, while he was "awake"
- Belief in the intercession of Muhammad being a reality on the Last Day
- Belief in God's covenant with Adam and his offspring having been "true"
- Belief in Abraham having been God's "intimate friend"
- Belief in Moses having conversed directly with God without a mediator
- Belief in the idea that wrong works in themselves does not make a Muslim an " unbeliever " and that it is forbidden to declare takfir on those who know that what they are doing is wrong
- Belief in it being wrong to "make a distinction" between the various prophets of God
- Belief in believing in that which "all the prophets" brought from God
- Belief in avoiding "deviations, divisions, and differences" in the fold of Islam
- Belief in venerating all the Companions of Muhammad
- Belief in the existence of saints , and in venerating them and accepting the traditional narratives of their lives and miracles (*)
- Belief that saints, while exalted in their own right, occupy an infinitely lesser rank than the prophets and that "one of the prophets is greater than all the saints put together" (*)
- Belief in the Signs of the Apocalypse
- Belief that Jesus is the Promised Messiah of God and that all Muslims await his Second Coming
Some Islamic scholars faced questions that they felt were not explicitly answered in the Quran and the Sunnah , especially questions with regard to philosophical conundra such as the nature of God , the existence of human free will , or the eternal existence of the Quran. Various schools of theology and philosophy developed to answer these questions, each claiming to be true to the Quran and the Muslim tradition ( sunnah ). Among Sunni Muslims, various schools of thought in theology began to be born out of the sciences of kalam in opposition to the textualists who stood by affirming texts without delving into philosophical speculation as they saw it as an innovation in Islam. The following were the three dominant schools of theology that grew. All three of these are accepted by Muslims around the globe, and are considered within "Islamic orthodoxy". The key beliefs of classical Sunni Islam are all agreed upon (being the six pillars of Iman) and codified in the treatise on Aqeedah by Imam Ahmad ibn Muhammad al-Tahawi in his Aqeedat Tahawiyyah .
Founded by Abu al-Hasan al-Ash'ari (873–935). This theological school of Aqeedah was embraced by many Muslim scholars and developed in parts of the Islamic world throughout history; the Imam al-Ghazali wrote on the creed discussing it and agreeing upon some of its principles. 
Ash'ari theology stresses divine revelation over human reason. Contrary to the Mu'tazilites, they say that ethics cannot be derived from human reason, but that God's commands, as revealed in the Quran and the Sunnah (the practices of Muhammad and his companions as recorded in the traditions, or hadith ), are the sole source of all morality and ethics.
Regarding the nature of God and the divine attributes, the Ash'ari rejected the Mu'tazili position that all Quranic references to God as having real attributes were metaphorical. The Ash'aris insisted that these attributes were as they "best befit His Majesty". The Arabic language is a wide language in which one word can have 15 different meanings, so the Ash'aris endeavor to find the meaning that best befits God and is not contradicted by the Quran. Therefore, when God states in the Quran, "He who does not resemble any of His creation," this clearly means that God cannot be attributed with body parts because He created body parts. Ash'aris tend to stress divine omnipotence over human free will and they believe that the Quran is eternal and uncreated.
Founded by Abu Mansur al-Maturidi (died 944). Maturidiyyah was a minority tradition until it was accepted by the Turkish tribes of Central Asia (previously they had been Ash'ari and followers of the Shafi'i school, it was only later on migration into Anatolia that they became Hanafi and followers of the Maturidi creed.) One of the tribes, the Seljuk Turks , migrated to Turkey , where later the Ottoman Empire was established.  Their preferred school of law achieved a new prominence throughout their whole empire although it continued to be followed almost exclusively by followers of the Hanafi school while followers of the Shafi and Maliki schools within the empire followed the Ash'ari and Athari schools of thought. Thus, wherever can be found Hanafi followers, there can be found the Maturidi creed.
Traditionalist theology is a movement of Islamic scholars who reject rationalistic Islamic theology ( kalam ) in favor of strict textualism in interpreting the Quran and sunnah .  The name derives from "tradition" in its technical sense as translation of the Arabic word hadith . It is also sometimes referred to by several other names .
Adherents of traditionalist theology believe that the zahir (literal, apparent) meaning of the Qur'an and the hadith have sole authority in matters of belief and law; and that the use of rational disputation is forbidden even if it verifies the truth. They engage in a literal reading of the Qur'an, as opposed to one engaged in ta'wil (metaphorical interpretation). They do not attempt to conceptualize the meanings of the Qur'an rationally, and believe that their realities should be consigned to God alone ( tafwid ). In essence, the text of the Qur'an and Hadith is accepted without asking "how" or " Bi-la kaifa ".
Traditionalist theology emerged among scholars of hadith who eventually coalesced into a movement called ahl al-hadith under the leadership of Ahmad ibn Hanbal . In matters of faith, they were pitted against Mu'tazilites and other theological currents, condemning many points of their doctrine as well as the rationalistic methods they used in defending them. In the tenth century al-Ash'ari and al-Maturidi found a middle ground between Mu'tazilite rationalism and Hanbalite literalism, using the rationalistic methods championed by Mu'tazilites to defend most tenets of the traditionalist doctrine.   Although the mainly Hanbali scholars who rejected this synthesis were in the minority, their emotive, narrative-based approach to faith remained influential among the urban masses in some areas, particularly in Abbasid Baghdad . 
While Ash'arism and Maturidism are often called the Sunni "orthodoxy", traditionalist theology has thrived alongside it, laying rival claims to be the orthodox Sunni faith.  In the modern era it has had a disproportionate impact on Islamic theology, having been appropriated by Wahhabi and other traditionalist Salafi currents and spread well beyond the confines of the Hanbali school of law. 
Sunni view of hadith
The Quran as it exists today in book form was compiled by Muhammad's companions ( Sahabah ) within a handful of months of his death, and is accepted by all sects of Islam. However, there were many matters of belief and daily life that were not directly prescribed in the Quran, but were actions that were observed by Muhammad and the early Muslim community. Later generations sought out oral traditions regarding the early history of Islam, and the practices of Muhammad and his first followers, and wrote them down so that they might be preserved. These recorded oral traditions are called hadith. Muslim scholars have through the ages sifted through the hadith and evaluated the chain of narrations of each tradition, scrutinizing the trustworthiness of the narrators and judging the strength of each hadith accordingly.
Kutub al-Sittah are six books containing collections of hadiths. Sunni Muslims accept the hadith collections of Bukhari and Muslim as the most authentic ( sahih , or correct), and while accepting all hadiths verified as authentic, grant a slightly lesser status to the collections of other recorders. There are, however, four other collections of hadith that are also held in particular reverence by Sunni Muslims, making a total of six:
- Sahih al-Bukhari of Muhammad al-Bukhari
- Sahih Muslim of Muslim ibn al-Hajjaj
- Sunan al-Sughra of Al-Nasa'i
- Sunan Abu Dawud of Abu Dawood
- Jami' at-Tirmidhi of Al-Tirmidhi
- Sunan Ibn Majah of Ibn Majah
There are also other collections of hadith which also contain many authentic hadith and are frequently used by scholars and specialists. Examples of these collections include:
- Musannaf of Abd al-Razzaq of ‘Abd ar-Razzaq as-San‘ani
- Musnad of Ahmad ibn Hanbal
- Mustadrak of Al Haakim
- Muwatta of Imam Malik
- Sahih Ibn Hibbaan
- Sahih Ibn Khuzaymah of Ibn Khuzaymah
- Sunan al-Darimi of Al-Darimi
There has also been a rich tradition of mysticism within Sunni Islam, which has most prominently manifested itself in the principal orders of Sunni Sufism . Historically, Sufism became "an incredibly important part of Islam" and "one of the most widespread and omnipresent aspects of Muslim life" in Islamic civilization from the early medieval period onwards,   when it began to permeate nearly all major aspects of Sunni Islamic life in regions stretching from India and Iraq to Senegal . Sufism continued to remain a crucial part of daily Islamic life until the twentieth century , when its historical influence upon Islamic civilization began to be combated by the rise of Salafism and Wahhabism . Islamic scholar Timothy Winter has remarked: "[In] classical, mainstream, medieval Sunni Islam ... [the idea of] 'orthodox Islam' would not ... [have been possible] without Sufism,"  and that the classical belief in Sufism being an essential component of Islam has only weakened in some quarters of the Islamic world "a generation or two ago" with the rise of Salafism .  In the modern world, the classical interpretation of Sunni orthodoxy, which sees in Sufism an essential dimension of Islam alongside the disciplines of jurisprudence and theology , is represented by institutions such as Al-Azhar University and Zaytuna College , with Al-Azhar's current Grand Imam Ahmed el-Tayeb defining "Sunni orthodoxy" as being a follower "of any of the four schools of [legal] thought ( Hanafi , Shafi’i , Maliki or Hanbali ) and ... [also] of the Sufism of Imam Junayd of Baghdad in doctrines, manners and [spiritual] purification." 
In the eleventh-century, Sufism, which had previously been a less "codified" trend in Islamic piety, began to be "ordered and crystallized" into orders which have continued until the present day. All these orders were founded by a major Sunni Islamic saint , and some of the largest and most widespread included the Qadiriyya (after Abdul-Qadir Gilani [d. 1166]), the Rifa'iyya (after Ahmed al-Rifa'i [d. 1182]), the Chishtiyya (after Moinuddin Chishti [d. 1236]), the Shadiliyya (after Abul Hasan ash-Shadhili [d. 1258]), and the Naqshbandiyya (after Baha-ud-Din Naqshband Bukhari [d. 1389]). Contrary to popular perception in the West, however, neither the founders of these orders nor their followers ever considered themselves to be anything other than orthodox Sunni Muslims, and in fact all of these orders were attached to one of the four orthodox legal schools of Sunni Islam.   Thus, the Qadiriyya order was Hanbali , with its founder, Abdul-Qadir Gilani , being a renowned Hanbali jurist; the Chishtiyya was Hanafi ; the Shadiliyya order was Maliki ; and the Naqshbandiyya order was Hanafi . Thus, "many of the most eminent defenders of Islamic orthodoxy, such as Abdul-Qadir Gilani , Ghazali , and the Sultan Ṣalāḥ ad-Dīn ( Saladin ) were connected with Sufism."