their perceived apostasy (ridda). In addition, there are several differences within Sunnī and Shīʿa Islam: Sunnī Islam is separated into four main schools of jurisprudence, namely Mālikī, Ḥanafī, Shāfiʿī, and Ḥanbalī; these schools are named after their founders Mālik ibn Anas, Abū Ḥanīfa al-Nuʿmān, Muḥammad ibn Idrīs al-Shāfiʿī , and Aḥmad ibn Ḥanbal, respectively. Shīʿa Islam, on the other hand, is separated into three major sects: Twelvers, Ismāʿīlīs, and Zaydīs. The vast majority of Shīʿa Muslims are Twelvers (a 2012 estimate puts the figure as 85%), to the extent that the term "Shīʿa" frequently refers to Twelvers by default. All mainstream Twelver and Ismāʿīlī Shīʿa Muslims follow the same school of thought, the Jaʽfari jurisprudence, named after Jaʿfar al-Ṣādiq, the sixth Shīʿīte Imam. Zaydīs, also known as Fivers, follow the Zaydī school of thought (named after Zayd ibn ʿAlī). Ismāʿīlīsm is another offshoot of Shīʿa Islam that later split into Nizārī and Musta‘lī, and the Musta‘lī further divided into Ḥāfiẓi and Ṭayyibi. Ṭayyibi Ismāʿīlīs, also known as "Bohras", are split between Dawudi Bohras, Sulaymani Bohras, and Alavi Bohras. Similarly, Kharijites were initially divided into five major branches: Sufris, Azariqa, Najdat, Adjarites, and Ibadis. Of these, Ibadi Muslims are the only surviving branch of Kharijites. In addition to the aforementioned groups, new schools of thought and movements like Ahmadi Muslims, Quranist Muslims, and African-American Muslims later emerged independently. Muslims who do not belong to, do not self-identify with, or cannot be readily classified under one of the identifiable Islamic schools and branches are known as non-denominational Muslims. Main branches or denominations Sunnī Islam Sunnī Islam, also known as Ahl as-Sunnah waʾl Jamāʾah or simply Ahl as-Sunnah, is by far the largest denomination of Islam, comprising around 85% of the Muslim population in the world. The term Sunnī comes from the word sunnah, which means the teachings, actions, and examples of the Islamic prophet Muhammad and his companions (ṣaḥāba). Sunnīs believe that Muhammad did not specifically appoint a successor to lead the Muslim community (Ummah) before his death in 632 CE, however they approve of the private election of the first companion, Abū Bakr. Sunnī Muslims regard the first four caliphs—Abū Bakr (632–634), ʿUmar ibn al-Khaṭṭāb (Umar І, 634–644), ʿUthmān ibn ʿAffān (644–656), and ʿAlī ibn Abī Ṭālib (656–661)—as al-Khulafā'ur-Rāshidūn ("the Rightly-Guided Caliphs"). Sunnīs also believe that the position of caliph may be attained democratically, on gaining a majority of the votes,