The Ottoman Empire ruled extensive territories. Administration, taxation, and justice involved communities with different religions and languages, and practices were not identical everywhere. Its borders and institutions changed over time, with nineteenth-century reforms introducing further arrangements. Understanding the empire requires attention to particular periods and regions rather than a fixed impression.

Government

Before the reforms of the 19th and 20th centuries, the state organisation of the Ottoman Empire was a system with two main dimensions, the military administration, and the civil administration. The Sultan was in the highest position in the system. The civil system was based on local administrative units based on the region's characteristics. The state had control over the clergy. Certain pre-Islamic Turkish traditions that had survived the adoption of administrative and legal practices from Islamic Iran remained important in Ottoman administrative circles. According to Ottoman understanding, the state's primary responsibility was to defend and extend the land of the Muslims and to ensure security and harmony within its borders in the overarching context of orthodox Islamic practice and dynastic sovereignty.

The Ottoman Empire, or as a dynastic institution, the House of Osman, was unprecedented and unequalled in the Islamic world for its size and duration. In Europe, only the House of Habsburg had a similarly unbroken line of sovereigns (kings/emperors) from the same family who ruled for so long, and during the same period, between the late 13th and early 20th centuries. The Ottoman dynasty was Turkish in origin.

Language

Ottoman Turkish was the official language of the Empire. It was an Oghuz Turkic language highly influenced by Persian and Arabic, though lower registries spoken by the common people had fewer influences from other languages compared to higher varieties used by upper classes and governmental authorities. Turkish, in its Ottoman variation, was a language of military and administration since the nascent days of the Ottomans. The Ottoman constitution of 1876 did officially cement the official imperial status of Turkish.

The Ottomans had several influential languages: Turkish, spoken by the majority of the people in Anatolia and by the majority of Muslims of the Balkans except some regions such as Albania, Bosnia and the Megleno-Romanian-inhabited Nânti; Persian, only spoken by the educated; Arabic, spoken mainly in Egypt, the Levant, Arabia, Iraq, North Africa, Kuwait and parts of the Horn of Africa and Berber in North Africa. In the last two centuries, usage of these became limited, though, and specific: Persian served mainly as a literary language for the educated, while Arabic was used for Islamic prayers. In the post-Tanzimat period French became the common Western language among the educated.

Because of a low literacy rate among the public (about 2–3% until the early 19th century and just about 15% at the end of the 19th century), ordinary people had to hire scribes as "special request-writers" (arzuhâlcis) to be able to communicate with the government. Some ethnic groups continued to speak within their families and neighbourhoods (mahalles) with their own languages, though many non-Muslim minorities such as Greeks and Armenians only spoke Turkish.

Religion

Sunni Islam was the prevailing Dīn (customs, legal traditions, and religion) of the Ottoman Empire; the official Madh'hab (school of Islamic jurisprudence) was Hanafi. From the early 16th century until the early 20th century, the Ottoman sultan also served as the caliph, or politico-religious leader, of the Muslim world. Most of the Ottoman Sultans adhered to Sufism and followed Sufi orders, and believed Sufism was the correct way to reach God.

Non-Muslims, particularly Christians and Jews, were present throughout the empire's history. The Ottoman imperial system was charactised by an intricate combination of official Muslim hegemony over non-Muslims and a wide degree of religious tolerance. While religious minorities were never equal under the law, they were granted recognition, protection, and limited freedoms under both Islamic and Ottoman tradition.

Until the second half of the 15th century, the majority of Ottoman subjects were Christian. Non-Muslims remained a significant and economically influential minority, albeit declining significantly by the 19th century, due largely to migration and secession. The proportion of Muslims amounted to 60% in the 1820s, gradually increasing to 69% in the 1870s and 76% in the 1890s. By 1914, less than a fifth of the empire's population (19.1%) was non-Muslim, mostly made up of Jews and Christian Greeks, Assyrians, and Armenians.