What Is Sunnism or Ahl as-Sunnah wa’l-Jamā‘h ?

Sunni Islam is the largest denomination of Islam . Sunni Islam is also referred to as Sunnism or as Ahl as-Sunnah wa’l-Jamā‘h (Arabic: أهل السنة والجماعة) (people of the example (of Muhammad) and the community), or Ahl as-Sunnah (Arabic: أهل السنة ) for short. The word Sunni comes from the word Sunnah (Arabic : سنة ), which means the words and actions [1] or example of the Islamic prophet Muhammad.

Historically, Sunni Islam has often been defined only in contrast with other denominations or schools of thought, such as Shia Islam, hanafiyah, Mu'tazila and others, considering itself to be the orthodox form of Islam.[citation needed] As such, a case is sometimes made that Sunnism is as old as Islam itself,[citation needed] or at least dates back to the first civil war in Islam from 656 to 661. However, in terms of doctrine and theology, and in the sense of considering itself a separate denomination, Sunni Islam is younger than that, making it somewhat misleading to talk about Sunnites in a 7th century context.
Sunni Islam was under the authority of the Caliph from Muhammad's death in 632 until the abolition of the caliphate by Mustafa Kemal Atatürk in 1924. Since then, no central international authority exists; many countries have a Grand Mufti or other official who holds the highest religious authority in the country. However, during all of Islam's history, independent religious scholars - the ulama - have held great influence in religious matters. During the first centuries of Islam, when the Umayyad and Abbasid caliphs were the worldly rulers of the Muslim world as well as the highest religious authorities of Sunni Islam, this led to some power struggles between the caliphate and the ulama. As the worldly power of the caliphate declined from the 9th and 10th century onwards, and as the religious law became more codified and exhaustive due to the efforts of the ulama, the caliphate's religious influence decreased as well.

Source :Wiki