Languages of the Ottoman Empire
The language of the court and government of the Ottoman Empire was Ottoman Turkish, but many other languages were in contemporary use in parts of the empire. Although the minorities of the Ottoman Empire were free to use their language amongst themselves, if they needed to communicate with the government they had to use Ottoman Turkish.
World language
The Romance languages bear testimony to the role of Latin as the "lingua franca" of the Roman Empire; for example, Italian has always been important in the Mediterranean region, and nowadays it is the most-spoken language among members of the Roman catholic hierarchy and it is also used in music (especially Opera) and the fashion industry. Turkish was similarly important as the primary language of the Ottoman Empire. Koine Greek was the "world language" of the Hellenistic period, but its distribution is not reflected in the distribution of Modern Greek due to the linguistic impact of the Slavic, Arabic and Turkic expansions. The distribution of the Arabic and Turkic languages, in turn, are a legacy of the Caliphates and the Turkic Khaganate, respectively.