Urdu (/ˈʊərduː/; Urdu: اُردُو Urdū; [ˈʊrd̪uː]), or more precisely Modern Standard Urdu, is a standardized register of the Hindustani language. Urdu is historically associated with the Muslims of the region of Hindustan. It is the national language and lingua franca of Pakistan, and an official language of five Indian states and one of the 22 scheduled languages in the Constitution of India. Apart from specialized vocabulary, Urdu is mutually intelligible with Standard Hindi, which is associated with the Hindu community. Since the end of the Mughal period in the nineteenth century, varieties of Hindustani have been the lingua franca for much of South Asia.
Urdu and Hindi are nearly identical in basic structure and grammar, and at a colloquial level also in vocabulary and phonology. If considered the same language, the population of Hindi-Urdu speakers is the fourth largest of the languages of the world, after Mandarin Chinese, English and Spanish. (Wikipedia)