Abstract is: Urdu (/ˈʊərduː/; Urdu: اُردُو, ALA-LC: Urdū) is an Indo-Aryan language spoken chiefly in South Asia. It is the national language and lingua franca of Pakistan, where it is also an official language alongside English. In India, Urdu is an Eighth Schedule language whose status and cultural heritage is recognized by the Constitution of India; it also has an official status in several Indian states. In Nepal, Urdu is a registered regional dialect. The Urdu language has been described as a Persianised register of the Hindustani language; Urdu and Hindi share a common Sanskrit- and Prakrit-derived vocabulary base, phonology, syntax, and grammar, making them mutually intelligible during colloquial communication. While formal Urdu draws literary, political, and technical vocabulary from Persian, formal Hindi draws these aspects from Sanskrit; consequently, the two languages' mutual intelligibility effectively decreases as the factor of formality increases. In 1837, the British East India Company chose Urdu as the language to replace Persian across northern India during Company rule; Persian had until this point served as the court language of various Indo-Islamic empires. Religious, social, and political factors arose during the European colonial period that advocated a distinction between Urdu and Hindi, leading to the Hindi–Urdu controversy. Urdu became a literary language in the 18th century and two similar standard forms came into existence in Delhi and Lucknow. Since the partition of India in 1947, a third standard has arisen in the Pakistani city of Karachi. Deccani, an older form used in Deccan, became a court language of the Deccan sultanates by the 16th century. According to 2018 estimates by Ethnologue, Urdu is the 10th-most widely spoken language in the world, with 230 million total speakers, including those who speak it as a second language.