Ottoman Caliphate in the context of "Istanbul"

A caliphate (Arabic: خلافة, romanized: khilāfa [xiˈlaːfa]) is an institution or public office under the leadership of an Islamic steward with the title of caliph (/ˈkælɪf, ˈkeɪ-/; خليفة khalīfa [xaˈliːfa], pronunciation), a person considered a political–religious successor to the Islamic prophet Muhammad and a leader of the entire Muslim world (ummah). Historically, the caliphates were polities based on Islam which developed into multi-ethnic trans-national empires.

During the medieval period, three major caliphates succeeded each other: the Rashidun Caliphate (632–661), the Umayyad Caliphate (661–750), and the Abbasid Caliphate (750–1517). In the fourth major caliphate, the Ottoman Caliphate, the rulers of the Ottoman Empire claimed caliphal authority from 1517 until the Ottoman Caliphate was formally abolished as part of the 1924 secularisation of Turkey. The Sharif of Mecca then claimed the title, but this caliphate fell quickly after its conquest by the Sultanate of Nejd (the predecessor of modern-day Saudi Arabia), leaving the claim in dormancy. Throughout the history of Islam, a few other Muslim states, almost all of which were hereditary monarchies, have claimed to be caliphates.

Sunni Islam was the official religion of the Ottoman Empire. The highest position in Islam, caliphate, was claimed by the sultan, after the defeat of the Mamluks which was established as Ottoman Caliphate. The sultan was to be a devout Muslim and was given the literal authority of the caliph. Additionally, Sunni clerics had tremendous influence over government and their authority was central to the regulation of the economy. Despite all this, the sultan also had a right to the decree, enforcing a code called Kanun (law) in Turkish. Additionally, there was a supreme clerical position called the Sheykhulislam ("Sheykh of Islam" in Arabic). Minorities, particularly Christians and Jews but also some others, were mandated to pay the jizya, the poll tax as mandated by traditional Islam.

Osmanoğlu family is a family belonging to the historical House of Osman, which was the ruling house of the Ottoman Empire from 1299 until the abolition of the Ottoman sultanate in 1922, and the Ottoman Caliphate from 1517 until the abolition of the caliphate in 1924. In 1924, members of the Osmanoğlu family were forced into exile. Their descendants now live in many countries throughout Europe, as well as in the United States, the Middle East, and since they have been permitted to return to their homeland, many now also live in Turkey. The female members of the dynasty were allowed to return after 1951, and the male members after 1973. The family adopted the surname of Osmanoğlu, meaning "son of Osman".

The Ottoman Caliphate, the world's last widely recognized caliphate, was abolished on 3 March 1924 (R.C. 1340, A.H. 1342) by decree of the Grand National Assembly of Turkey. The process was one of Atatürk's reforms following the replacement of the Ottoman Empire with the Republic of Turkey. Abdülmecid II was deposed as the last Ottoman caliph.

The caliph was nominally the supreme religious and political leader of all Sunni Muslims across the world. In the years prior to the abolition, during the ongoing Turkish War of Independence, the uncertain future of the caliphate provoked strong reactions among the worldwide community of Sunni Muslims. The potential abolition of the caliphate had been actively opposed by the Indian-based Khilafat Movement, and generated heated debate throughout the Muslim world. The 1924 abolition came about less than 18 months after the abolition of the Ottoman sultanate, prior to which the Ottoman sultan was ex officio caliph.

The Sharifian Caliphate (Arabic: الخلافة الشريفية, romanized: al-Khilāfat al-Sharīfiyya) was a Caliphate proclaimed by the Sharifian leaders of the Hejaz in 1924, replacing the Ottoman Caliphate, which was abolished by the Grand National Assembly of Turkey. Even though the Banu Hashim held the caliphate at various points in history, Hussein bin Ali, the Sharif of Mecca, was the first and last caliph of this lineage.

In the Arab world, it represented the culmination of a long struggle to reclaim the caliphate from Ottoman hands. The first Arab revolts challenging the validity of the Ottoman caliphate and demanding that an Arab Sayyid be chosen as caliph can be traced back to 1883 when Sheikh Hamat-al-Din seized Sanaa and called for the caliphate as a Sayyid.