Kharijites
Kharijites were members of an Islamic sect in late 7th and early 8th century AD, concentrated in today's southern Iraq. They were distinct from the Sunni and Shiites.
The origins of Kharijites lie in the strife over political supremacy over the Muslim community in the years following the death of Muhammad. The third Caliph, Uthman ibn Affan, was killed by mutineers in 656 AD, and a struggle for succession ensued between Ali, the cousin and son-in-law of Muhammad, and Mu'awiya, governor of Damascus. (The core of Ali's followers later became Shiites.) In 658, Ali's forces met Muawiya's at the Battle of Siffin; at first, the battle went against Muawiya, but then he hit upon the idea of having his army hoist Qur'ans on their lances, proclaiming that he wanted to have the decision of who should be caliph arbitrated using it. Most of Ali's army was favorable to the idea, and he agreed to have the question decided by two arbiters. Some in his army, however, regarded this as a betrayal; a large group of them (traditionally 12,000, mainly from the Tamim tribe) repudiated his cause, leaving to fight both sides; they became known as Kharijites (in Arabic Khawārij, singular Khārijī, meaning 'those that seceded'). Ali defeated the military rebellion, but the Kharijites survived and an adherent of the movement murdered Ali in 661.
Kharijite theology was a form of radical fundamentalism, preaching uncompromising observance of the teachings of Qur'an in defiance of corrupt authorities. Extreme Kharijites considered moderate Muslims to be 'hypocrites' or 'unbelievers', who could be killed with impunity; this practice is called takfir. Their communities expelled from their midst those who committed 'grave sins', defined as any action contrary to the Qur'an. Kharijites insisted that only the most pious members of the community should be entrusted with political power. Perhaps not surprisingly, the various Kharijite communities never agreed on who the most pious person was, and the movement remained politically fragmented throughout its existence.
With time the movement became more moderate and less antagonistic to mainstream Islam. The high point of the Kharijites' influence was in the years 690 to 730, when their main city, Basra, became a center of Islamic theology. Kharijite ideology became a popular creed for rebels against the officially Sunni Caliphate, inspiring breakaway states (like the Rustamids and the Midrarids) and rebellions (like Maysara's) throughout the Maghreb and sometimes elsewhere.
Three of the main Kharijite sects were named by color: the "white" Ibadis (still extant), the Azraqis, and the "yellow" Sufris (who established the Midrarid state at Sijilmassa.) However, this is probably a coincidence, as they are said to be named after their respective founders.
One "Kharijite" sect, the Ibadis, have survived into the present day (though they reject the designation "Kharijite".) They form a significant part of the population of Oman, and there are smaller concentrations of them in the Mzab of Algeria, Jerba in Tunisia, and Djebel Nafusa in Libya.
In modern times, Islamist writers have sometimes branded terrorist groups which emphasize the practice of takfir as neo-Kharijites; notable examples of groups described as such include the Groupe Islamique Armée of Algeria and the Takfir wal-Hijra group of Egypt.