Hindustani[d] is an Indo-Aryan language spoken in North India and Pakistan, and functioning as the lingua franca of the region.

Hindustani is a pluricentric language with two standard registers, known as Hindi (written in Devanagari script and influenced by Sanskrit) and Urdu (written in Perso-Arabic script and influenced by Persian and Arabic) which serve as official languages of India and Pakistan, respectively.

[20][21] In modern times, a third variety of Hindustani with significant English influences has also appeared, which is sometimes called Hinglish or Urdish.

[30] Scholars trace the language's first written poetry, in the form of Old Hindi, to the Delhi Sultanate era around the twelfth and thirteenth century.

[31][32][33] During the period of the Delhi Sultanate, which covered most of today's India, eastern Pakistan, southern Nepal and Bangladesh[34] and which resulted in the contact of Hindu and Muslim cultures, the Sanskrit and Prakrit base of Old Hindi became enriched with loanwords from Persian, evolving into the present form of Hindustani.

[57] The total number of Hindi–Urdu speakers was reported to be over 300 million in 1995, making Hindustani the third- or fourth-most spoken language in the world.

[35][40] Hindustani emerged as a contact language around the Ganges-Yamuna Doab (Delhi, Meerut and Saharanpur), a result of the increasing linguistic diversity that occurred during the Muslim period in the Indian subcontinent.

[75] Hindustani retained the grammar, as well as the core Sanskritic and Prakritic vocabulary, of the local Indian language of the Ganges-Yamuna Doab called Khariboli.

[59][35][75][76][77] However, as an emerging common dialect, Hindustani absorbed large numbers of Persian, Arabic, and Turkic loanwords, and as Mughal conquests grew it spread as a lingua franca across much of northern India; this was a result of the contact of Hindu and Muslim cultures in Hindustan that created a composite Ganga-Jamuni tehzeeb.

[38][36][39][78] The language was also known as Rekhta, or 'mixed', which implies that the Sanskritic and Prakritic vocabulary base of Old Hindi was mixed with Persian loanwords.

[76][35][37][59][79][80] Written in the Perso-Arabic, Devanagari,[81] and occasionally Kaithi or Gurmukhi scripts,[82] it remained the primary lingua franca of northern India for the next four centuries, although it varied significantly in vocabulary depending on the local language.

[82] In the 18th century, towards the end of the Mughal period, with the fragmentation of the empire and the elite system, a variant of Hindustani, one of the successors of apabhraṃśa vernaculars at Delhi, and nearby cities, came to gradually replace Persian as the lingua franca among the educated elite upper class particularly in northern India, though Persian still retained much of its pre-eminence for a short period.

While the first literary works (mostly translations of earlier works) in Sanskritised Hindustani were already written in the early 19th century as part of a literary project that included both Hindu and Muslim writers (e.g. Lallu Lal, Insha Allah Khan), the call for a distinct Sanskritised standard of Hindustani written in Devanagari under the name of Hindi became increasingly politicised in the course of the century and gained pace around 1880 in an effort to displace Urdu's official position.

Next to English it was the official language of British Indian Empire, was commonly written in Arabic or Persian characters, and was spoken by approximately 100,000,000 people.

[90] As Muslim rule expanded, Hindustani speakers traveled to distant parts of India as administrators, soldiers, merchants, and artisans.

In Dakhani, aspirated consonants were replaced with their unaspirated counterparts; for instance, dekh 'see' became dek, ghula 'dissolved' became gula, kuch 'some' became kuc, and samajh 'understand' became samaj.

[92] More recently, the word 'Hindustani' has been used for the colloquial language of Bollywood films, which are popular in both India and Pakistan and which cannot be unambiguously identified as either Hindi or Urdu.

[13] Hindustani is the lingua franca of the north and west of the Indian subcontinent, though it is understood fairly well in other regions also, especially in the urban areas.

One might reasonably assume that the Hindustani spoken in Lucknow, Uttar Pradesh (known for its usage of Urdu) and Varanasi (a holy city for Hindus and thus using highly Sanskritised Hindi) is somewhat different.

It is written, except in some parts of India, in the Nastaliq style of the Urdu alphabet, an extended Perso-Arabic script incorporating Indic phonemes.

The term bazaar Hindustani, in other words, the 'street talk' or literally 'marketplace Hindustani', also known as Colloquial Hindi[e] or Simplified Urdu,[f] has arisen to denote a colloquial register of the language that uses vocabulary common to both Hindi and Urdu while eschewing high-register and specialized Arabic or Sanskrit derived words.

Rekhta ('mixture'), Hindi ('Indian'), Hindustani, Hindvi, Lahori, and Dakni (amongst others) became popular names for the same language until the 18th century.

Grierson, in his highly influential Linguistic Survey of India, proposed that the names Hindustani, Urdu, and Hindi be separated in use for different varieties of the Hindustani language, rather than as the overlapping synonyms they frequently were: We may now define the three main varieties of Hindōstānī as follows:—Hindōstānī is primarily the language of the Upper Gangetic Doab, and is also the lingua franca of India, capable of being written in both Persian and Dēva-nāgarī characters, and without purism, avoiding alike the excessive use of either Persian or Sanskrit words when employed for literature.

In the post-independence period however, the term Hindustani has lost currency and is not given any official recognition by the Indian or Pakistani governments.

(In this context, "Union" means the Federal Government and not the entire country[citation needed]—India has 23 official languages.)

Although English is spoken by many, and Punjabi is the native language of the majority of the population, Urdu is the lingua franca.

Besides being the lingua franca of North India and Pakistan in South Asia,[14][44] Hindustani is also spoken by many in the South Asian diaspora and their descendants around the world, including North America (e.g., in Canada, Hindustani is one of the fastest growing languages),[108] Europe, and the Middle East.