Hindi (Devanāgarī: हिन्दी or हिंदी, IAST: Hindī) is the name given to an Indo-Aryan language, or a dialect continuum of languages, spoken in northern and central India (the "Hindi belt").

Native speakers of Hindi dialects form 41% of the Indian population (2001 Indian census). As defined in the Constitution, Hindi is the official language of India and is one of the 22 scheduled languages specified in the Eighth Schedule to the Constitution. Official Hindi is often described as Standard Hindi, which is used, along with English, for administration of the central government. Standard Hindi is a sanskritised register derived from the khari boli dialect. Urdu is a different, persianised, register of the same dialect. However, speakers of the two dialects can easily communicate. Taken together, these registers are historically also known as Hindustani.

Source - Wikipeadia.com