a  : The full style of the Ottoman ruler was complex, as it was composed of several titles and evolved over the centuries. The title of sultan was used continuously by all rulers almost from the beginning. However, because it was widespread in the Muslim world, the Ottomans quickly adopted variations of it to dissociate themselves from other Muslim rulers of lesser status. Murad I, the third Ottoman monarch, styled himself sultan-i azam (سلطان اعظم, the most exalted sultan) and hüdavendigar (خداوندگار, emperor), titles used by the Anatolian Seljuqs and the Mongol Ilkhanids respectively. His son Bayezid I adopted the style Sultan of Rûm, Rûm being an old Islamic name for the Roman Empire. The combining of the Islamic and Central Asian heritages of the Ottomans led to the adoption of the title that became the standard designation of the Ottoman ruler: Sultan [Name] Khan.[64] Ironically, although the title of sultan is most often associated in the Western world with the Ottomans, people within Turkey generally use the title of padishah far more frequently when referring to rulers of the Ottoman Dynasty.[65] b   : The Ottoman Caliphate was one of the most important positions held by rulers of the Ottoman Dynasty. The caliphate symbolized their spiritual power, whereas the sultanate represented their temporal power. According to Ottoman historiography, Murad I adopted the title of caliph during his reign (1362 to 1389), and Selim I later strengthened the caliphal authority during his conquest of Egypt in 1516-1517. However, the general consensus among modern scholars is that Ottoman rulers had used the title of caliph before the conquest of Egypt, as early as during the reign of Murad I (1362–1389), who brought most of the Balkans under Ottoman rule and established the title of sultan in 1383. It is currently agreed that the caliphate "disappeared" for two-and-a-half centuries, before being revived with the Treaty of Küçük Kaynarca, signed between the Ottoman Empire and Catherine II of Russia in 1774. The treaty was highly symbolic, since it marked the first international recognition of the Ottomans' claim to the caliphate. Although the treaty made official the Ottoman Empire's loss of the Crimean Khanate, it acknowledged the Ottoman caliph's continuing religious authority over Muslims in Russia.[66] From the 18th century onwards, Ottoman sultans increasingly emphasized their status as caliphs in order to stir Pan-Islamist sentiments among the empire's Muslims in the face of encroaching European imperialism. When World War I broke out, the sultan/caliph issued a call for jihad in 1914 against the Ottoman Empire's Allied enemies, unsuccessfully attempting to incite the subjects of the French, British and Russian empires to revolt. Abdülhamid II was by far the Ottoman sultan who made the most use of his caliphal position, and was recognized as caliph by many Muslim heads of state, even as far away as Sumatra.[67] He had his claim to the title inserted into the 1876 Constitution (Article 4).[68] c  : Tughras were used by 35 out of 36 Ottoman sultans, starting with Orhan in the 14th century, whose tughra has been found on two different documents. No tughra bearing the name of Osman I, the founder of the empire, has ever been discovered,[69] although a coin with the inscription "Osman bin Ertuğrul" has been identified.[17] Abdülmecid II, the last Ottoman caliph, also lacked a tughra of his own, since he did not serve as head of state (that position being held by Mustafa Kemal, President of the newly founded Republic of Turkey) but as a religious and royal figurehead. d : The Ottoman Interregnum, also known as the Ottoman Triumvirate (Turkish: Fetret Devri), was a period of chaos in the Ottoman Empire which lasted from 1402 to 1413. It started following the defeat and capture of Bayezid I by the Turco-Mongol warlord Tamerlane at the Battle of Ankara, which was fought on 20 July 1402. Bayezid's sons fought each other for over a decade, until Mehmed I emerged as the undisputed victor in 1413.[70] e : The dissolution of the Ottoman Empire was a gradual process which started with the abolition of the sultanate and ended with that of the caliphate 16 months later. The sultanate was formally abolished on 1November1922. Sultan Mehmed VI fled to Malta on 17November aboard the British warship Malaya.[60] This event marked the end of the Ottoman Dynasty, not of the Ottoman State nor of the Ottoman Caliphate. On 18November, the Grand National Assembly (TBMM) elected Mehmed VI's cousin Abdülmecid II, the then crown prince, as caliph.[71] The official end of the Ottoman State was declared through the Treaty of Lausanne (24July1923), which recognized the new "Ankara government," and not the old Istanbul-based Ottoman government, as representing the rightful owner and successor state. The Republic of Turkey was proclaimed by the TBMM on 29October1923, with Mustafa Kemal as its first President.[72] Although Abdülmecid II was a figurehead lacking any political power, he remained in his position of caliph until the office of the caliphate was abolished by the TBMM on 3March1924.[68] Mehmed VI later tried unsuccessfully to reinstall himself as caliph in the Hejaz.[73]

Constitutionalism was only established during the reign Abdul Hamid II, who thus became the empire's last absolute ruler and its reluctant first constitutional monarch.[12] Although Abdul Hamid II abolished the parliament and the constitution to return to personal rule in 1878, he was again forced in 1908 to reinstall constitutionalism and was deposed. Since 2017, the head of the House of Osman and pretender to the defunct Ottoman throne has been Dündar Ali Osman, a great-grandson of Abdulhamid II.[13]