Wahhabism (Arabic: وهابية, Wahhābiyyah) is a conservative branch of Sunni Islam. It is a religious movement among fundamentalist Islamic believers, with an aspiration to return to the primordial fundamental Islamic sources Quran, Hadith and scholarly consensus (Ijma). Wahhabism was a popular revivalist movement instigated by an eighteenth century theologian, Muhammad ibn Abd al-Wahhab (1703–1792) from Najd, Saudi Arabia. He began his movement through peaceful discussions with attendees of various shrines and eventually gained popular support by convincing the local Amir, Uthman ibn Mu'ammar, to help him in his struggle. Ibn Abd Al-Wahhab advocated a popular purging of the widespread practices by Muslims being what he considered to be impurities and innovations in Islam. It is claimed that this was carried out by some of his more extreme followers by the killing of innocent Sunni Muslims however this is fiercely debated. His has become the dominant form of Islam in Saudi Arabia. The movement claims to adhere to the correct understanding of the general Islamic doctrine of Tawhid, on the "uniqueness" and "unity" of God, shared by the majority of Islamic sects, but with an emphasis on advocating following of the Athari school of thought only. Ibn Abd-al-Wahhab was influenced by the writings of Ibn Taymiyya and questioned the prevalent philosophical interpretations of Islam being the Ash'ari and Maturidi schools, claiming to rely on the Qur'an and the Hadith without speculative philosophy so as to not transgress beyond the limits of the early Muslims known as the Salaf. He attacked a "perceived moral decline and political weakness" in the Arabian Peninsula and condemned what he perceived as idolatry, the popular cult of saints, and shrine and tomb visitation.
The terms Wahhabi and Salafi and ahl al-hadith (people of hadith) are often used interchangeably, but Wahhabism has also been called "a particular orientation within Salafism", an orientation considered ultra-conservative and apolitical.
The movement gained unchallenged precedence in the Arabian peninsula through an alliance between Muhammad ibn Abd al-Wahhab and the House of Muhammad ibn Saud who provided political and financial power for the religious revival represented by Ibn Abd al-Wahhab. The writer El Khabar Ousbouî suggests the popularity of the Wahhabi movement is in part due to this alliance and the funding of several religious channels.