Among the indicative of divisions or distinctions, the words used in the Koran are hizb (pl. ahzab), ta'ifa, shi'a and the derivatives of f-q-r. All can be understood with the general meaning of party, group or faction. The word hizb in its singular, plural and dual forms appears 19 times and the word shi'a and shi'ya occurs 11 times in the Koran. The word ta'ifa and its dual forms appears 23 times, used more or less randomly to refer to groups or parties among the Ahl al-Kitab. Tusi (d. 460/1067) calls the Shi'ites "the group which is right" (al-ta'ifa al-muhaqqiqa).

In Koran (3:23), the word fariq is used in the meaning of a faction. The one occurrence of firqa refers to a unit among the believers: "The believers should not go out together to fight, of every firqa of them a ta'ifa should remain behind to acquire religious knowledge" (9:122), "After the hearts of a fariq among them had almost turned away" (9:117). The word firaq (sing. firqa) is a noun from the Arabic verbal stem furaqa means split, divide or differentiate. In his book al-Farq bain al-firaq, al-Baghdadi used the word firqa means sect. So does al-Shahristani in his al-milal wa al-nihal when he used the word milla to mean nation, he used the word nihla to mean religious order. 

According to the famous tradition, "The Jews are divided into 71 sects, the Christians into 72 sects, and my people will be divided into 73 sects." This tradition is recorded with some variations in wording in many sources, namely Masnad (2:332, 3:120 & 4:102) by Ahmad bin Hanbal, Sahih (5:25-26) by Tirmizi, Sunan (2:503) by Abu Daud, Sunan (2:1321-2) by Ibn Majah, Sunan (2:241) by Darimi, Mustadrak (4:430) by Hakim, Mishkat (1:61) by Khatib Tabrizi, Majma'az Zawa'id (7:157, 159) by al-Hathami, al-Kafi (8:224) by Kulaini, etc. Once Imam Jafar Sadik was asked, "Why Muslims are disunited?" The Imam asked, "Were they disunited in the period of the Prophet?" The man said, "No." The Imam said, "Because they were obeying a single order of the Prophet and not going here and there in the matter of religion, and therefore, the unity of religion is possible only under the divine guidance of the Prophet and the Imam of the time after him."

A few of the recognized authorities on the sects of Islam are:- Al-Maqalat wal firaq by al-Qummi (d. 301/914), Kitab Firaq al-Shi'a by Nawbakhti (d. 310/922), Maqalat al-Islamiyyin by al-Ashari (d. 324/935), Kitab al-tanbih wal-radd by al-Malati (d. 377/987), Al-Farq bain al-Firaq by al-Baghdadi (d. 429/1037), Kitab al-milal wal nihal by Ibn Hazm (d. 456/1064), Kitab al-milal wal nihal by Shahristani (d. 548/1153), Dabistan al-Madhahib by Mohsin Fani (d. 1081/1670), etc. The following sects emerged in the mainstream of ummah:-

Sunni : Hanafi, Shafi, Maliki and Hanbali

Shi'ite : Ithna Asharis, Ismailis, Bohra, Alwi, Abadia, Abbasia, Kaisaniya, Zaidia, Matnasakhia, Mut'razia, Tania, Razia and Ishaqia.

Kharji : A'zarkia, Abardia, Salabia, Kharzamia, Khalafia, Karzia, Mut'zilla, Maimunia, Mahokamia, Shamrakhia, Naoshia and La'amina.

Jabaria : Muztaria, Magfiria, Jebia, Sabakia, Kaslia, Khofia, Fakaria, Hasabia, Mairamia, A'haiyya, Mo'haiyyia and Afalia.

Qadaria : Ahmadia, Sanavia, Kisania, Setania, Sharkia, Abadia, Nakasia, Tabaria, Kastia, Lazamia, Manzamiya and Wahemia. 

Murjia : Tehmia, Almia, Rajia, Tarkia, Mashaikhia, Sakia, Manshia, Murtrawia, Ashrabia and 

Baduwia.

Jahamia : Moaltia, Marabandia, Mutrafia, Varidia, Hurufia, Makhlukia, Gairia, Fatiyya, Zanvakia, Lafzia and Waqifia.