Hindi-Urdu (हिंदी उर्दू, ہندی اردو) is an Indo-Aryan language and the lingua franca of North India and Pakistan. It is also known as Hindustani (हिन्दुस्तानी, ہندوستانی, Hindustānī, IPA: [ɦɪ̃n̪d̪ʊsˈt̪aːni], literally: "of Hindustan"), and historically, as Hindavi or Rekhta. It derives primarily from the Khariboli dialect of Delhi, and incorporates a large amount of vocabulary from Persian, Arabic, Sanskrit and Turkic. It is a pluricentric language, with two official forms, Standard Hindi and Standard Urdu, which are standardized registers of it. Colloquial Standard Hindi and Urdu are all but indistinguishable, and even the official standards are nearly identical in grammar, though they differ in literary conventions and in academic and technical vocabulary, with Urdu retaining stronger Persian, Central Asian and Arabic influences, and Hindi relying more heavily on Sanskrit. Before the Partition of British India, the terms Hindustani, Urdu and Hindi were synonymous; all covered what would be called Urdu and Hindi today. The term "Hindustani" is also used for several quite different varieties of Hindi spoken outside of the Subcontinent, including Fijian Hindustani and the Caribbean Hindustani of Suriname and Trinidad.

Hindustani people (People of Hindustan), also known as Hindavi (People of Hind) are a panethnicity primarily living in the Hind Region of India also known as the Hindi belt, which is located in the Gangetic Plain of North India, between the Himalayas and the Vindhyas. They are identified as such on one or more of genealogical, linguistic, or cultural grounds. Traditionally, Hindustani or Hindavi identity is primarily cultural, with Hindustanis or Hindavis being those who the Hindi Language with any variety of Hindi is their prime language — mainly residing in present day Indian States of Bihar, Jharkhand, Uttarakhand, Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Haryana & Delhi. in other words the Hindi belt. The Hindustani or Hindavi People seems to be of ethnolinguistic in origin rather than as an ethnic group but certain Indo-Aryan ethnic groups are identified as Hindustani people.

If the diverse Hindustani pan-ethnicity is regarded as a single ethnic group, then it constitutes one of the world's largest.