Variations in the pronunciation of several phonemes are affected by the regional tongues (see Languages of India) across the subcontinent, the greatest distinction being that between South India and Sri Lanka on the one hand and the north of the subcontinent (including Pakistan, North India and Bangladesh) on the other. Several idiomatic forms crossing over from Indian literary and vernacular language also have made their way into the English of the masses. In spite of India's diversity, however, there is indeed a general homogeneity in syntax and vocabulary that can be found among speakers across South Asia. It will be found that excellent English bearing less regional grammatical peculiarities is spoken in upper-class families (commonly referred to, in India, as 'Westernised'), though even among them hints of a uniquely Indian flavor (particularly in a so-called 'Indianised' British accent) are typically retained.
Influences: British and American
The form of English that Indians (and other subcontinentals) are taught in schools is essentially British English. The Indian government though, accepts both forms of spellings as 'correct' English and makes no distinction. However, for most, it is desirable to emulate the brand of English that is linguistically known as Received Pronunciation or, more commonly, BBC English. In particular, Indian spellings follow British conventions to the point at which American English variations are considered untenable. However, even during the time of British imperialism (before the creation of a separate Pakistan and Bangladesh), Indian English had established itself as an audibly distinct dialect with its own quirks and specific phrases. Following the departure of the British from India in 1947, Indian English took on a divergent evolution and many phrases that the British may consider antiquated are still popular in India. Official letters continue to include phrases like "please do the needful", "you will be intimated shortly", and "your obedient servant". This difference in style, though, is not as marked a difference as between British and American English (and unlike Canadian or Australian English there is no variation in spelling whatsoever.) Older British writers who made creative (and comical) use of now obsolete forms of colloquial English, like P. G. Wodehouse, and others who were en vogue fifty years ago, like Thomas Hardy, are immensely popular in India. British writer, journalist and wit Malcolm Muggeridge once joked that the last Englishman would be an Indian.
American English, due to the burgeoning influence of American pop culture on the rest of the world, has begun challenging traditional British English as the premier brand of English spoken in the Indian subcontinent, though this is largely limited to the youth in the last decade or two. The proliferation of "MTV culture," especially through pop and hip hop, and the increasing desire of Indians to attend US, as opposed to British, collegiate institutions for higher education, is leading to the spread of more emulation of American English among Indian youth. Also, the economic and political puissance of the U.S. often leads to heated debates as to whether or not British English or American English is the more practical accent for emigré Indians to adopt. It must be stressed, however, that British English retains its hold on the majority of Indians, particularly those of the older generation.
In a survey (  (http://www.postcolonialweb.org/india/hohenthal/5.4.html)), it was found that "the majority of the informants (70%) felt that RP (Received Pronunciation: BBC English; Standard English in Britain) would serve as the best model for Indian English, 10% thought General American English (ed. standard American English) would be better, and 17% preferred the Indian variety of English."
Indians and English literature
Spoken Indian English is often the butt of jokes by "educated" British, American and Indian English-speakers alike as is evidenced by such characters as Peter Sellers' Indian party-goer in the movie The Party and the Simpsons' convenience-store owner Apu Nahasapeemapetilon; there is also no dearth of jokes among Indians 'riffing' the pronunciation and idiomatic inconsistencies of Indian English (see External Links at bottom).
However, in spite of banter regarding colloquial English, India has a consistent and long record of pre- and post-Independence thinkers and writers whose writings and speeches are attestations to many Indians' absolute mastery of the language. Among others, Swami Vivekananda, Rabindranath Tagore, Shri Aurobindo Ghosh, Jawaharlal Nehru, the world-famous novelist R K Narayan, and Sarvepalli Radhakrishnan come to mind as prominent figures whose English, often though not always written, was of the highest quality in any country. Many more contemporary Indians, such as Vikram Seth and Salman Rushdie, are acknowledged masters of English literary style. Indian English writers and English writers of Indian origin – notably Booker Prize winners Salman Rushdie and Arundhati Roy – have in addition made creative use of more stereotypical Indian English through the mouths of characters in their works.
"An Indian English Grammar"
Standard English in India is prized and found plentifully in educated circles and higher Indian writing in English. Middle and upper-class Indians, especially those with greater exposure to the West through books, electronic media (such as television or movies) and travel, tend to speak more grammatically-standard English. British English is an official language of central and state governments in India. What is characterized as Indian English is not considered "correct usage" by either government-related institutions (such as offices and schools) or educated Indians who prize 'proper' English. Indian schools still teach grammar from (frequently older) British textbooks like Wren & Martin or J. C. Nesfield (1898): the grammar of higher British English is considered the only correct one. Efforts by the Oxford University Press to publish a dictionary of Indian English were an abject failure since customers in India preferred the 'proper' British dictionary. Spoken and written English in India has not explicitly "forked" away from British English because the labelling of English as a "foreign language" is part of many people's political attitudes: its explicit indigenisation would devalue efforts to discontinue the widespread use of English in India.
However, in spite of the great stress on good English in higher circles, the layman's spoken variety, Indian English, is wide-spread and well-known for its many eccentricities. For this reason, "grammar of Indian English" must be taken with a grain of salt. Indian accents vary greatly from those leaning more towards a purist British to those leaning more towards a more 'vernacular' (Indian language)-tinted speech. The most ubiquitous instance of modified sounds is the morphing of alveolar English 'd', 't' and 'r' sounds to more retroflex variants. South Indians tend to curl the tongue more for 'l' and 'n' sounds, while Bengalis (from both India and Bangladesh) often substitute 'j' for 'z' (as in 'jero' instead of 'zero'). Subcontinentals, especially those from the Sindh (of both India and Pakistan), have the habit of changing 'w' sounds to 'v' (as in 'ven' instead of 'when').
The distinct evolution of regional variations in contemporary usage has led to terms such as Hinglish (Hindi + English) and Tanglish (Tamil + English). These terminologies are often referred to in a humorous way, but at times they also have a derogatory connotation, with each region or stratum of society having fun at the expense of others. Hinglish, Tanglish, Benglish (Bengali + English) and other unnamed variations are particularly capitalised and made popular in the field of advertising. Here, the aim of reaching a large cross-section of society is fulfilled by such double-coding. There are thus many borrowed words from Indian languages that do find their way into popular writing, ads and newspapers, not to mention TV spots and shows.
Grammar, idiom and usage in Indian English
For those aware of the grammar of Indian tongues like Bengali, Hindi and Tamil, the logic behind quirks of Indian English is quite transparent and readily explicable. However, observation by the perspicacious, in spite of ignorance of Indian languages, will reveal much that is characterizable in 'rules' and 'tendencies.' One John M. Lawler of the University of Michigan observes the following anomalies in the grammar of Indian English:
In addition to Lawler's observations, other unique patterns are also standard and will frequently be encountered in Indian English:
Titles (of respect; formal)
Interjections & casual references
A few words unique to or originating in Indian English
Indians frequently inject words from Indian languages, such as Bengali, Hindi, Punjabi, Tamil and Urdu, into English. While the currency of such words usually remains restricted to Indians and other Indian subcontinentals, there are many which have been regularly entered into the Oxford English Dictionary as their popularity extended into worldwide mainstream English. Some of the more common examples are "jungle", "bungalow", "bandana", "mango", "pyjama"; others were introduced via the transmission of Indian religions like Hinduism and Buddhism, examples of which are "karma", "dharma", "pundit", "guru" and "swami".
Words unique to (i.e. not generally well-known outside South Asia) and/or popular in India include those in the following by no means exhaustive list: