Urdu (; Urdu: اُردُو‎, ALA-LC: Urdū) is an Indo-Aryan language spoken chiefly in South Asia. It is the official national language and lingua franca of Pakistan. In India, Urdu is an Eighth Schedule language whose status, function, and cultural heritage is recognized by the Constitution of India; it has some form of official status in several Indian states. In Nepal, Urdu is a registered regional dialect.

Urdu has been described as a Persianised standard register of the Hindustani language. Urdu and Hindi share a common Indo-Aryan vocabulary base, phonology and syntax, making them mutually intelligible in colloquial speech. While formal Urdu draws literary and technical vocabulary from Persian, formal Hindi draws these from Sanskrit.

Urdu was chosen as the language of East India Company rule across northern India in 1837 when the Company chose it to replace Persian, the court language of the Indo-Islamic empires. Religious, social, and political factors arose during the colonial period that advocated for 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 1947 a third standard has arisen in Karachi. Deccani, an older form used in the south, became a court language of the Deccan Sultanates in the 16th century.

According to Nationalencyklopedin's 2010 estimates, Urdu is the 21st most spoken first language in the world, with approximately 66 million who speak it as their native language. According to Ethnologue's 2018 estimates, Urdu is the 11th most widely spoken language in the world, with 170 million total speakers, including those who speak it as a second language.