Ottoman Turkish was the official language of the Ottoman Empire (1299-1918). Its foundation is Anatolian Turkish, into which Arabic and Persian elements were incorporated. It is therefore also referred to as a mixed language. Notably, the Arabic and Persian words are not only integrated as individual borrowings into the base language (Turkish), but are retained as complete phrases. Ottoman Turkish is a multifaceted language that was used in everyday conversations and folk literature as well as in classical Ottoman literature, administration, and diplomatic correspondence. Through various waves of language reform, modern Turkish developed from it. Today, Ottoman Turkish is the key to the rich literature of the Ottoman Turks as well as to primary sources on culture, economy, and politics.