Indian English is a catch-all phrase for dialects or varieties of English spoken widely in India.
The language Indians are taught in schools is essentially British English and in particular spellings follow British conventions. However, the British left India in 1947, and as a result many phrases that the British may consider antique 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". Older writers who made creative (and comical) use of now obsolete forms of colloquial English, like P. G. Wodehouse, are immensely popular too, as is cricket terminology like "googly" and "bouncer".
In addition, Indian English mixes in various words from Indian languages: "bandh" or "hartal" for strikes, "challan" for a monetary receipt or a traffic ticket, and so on. Several such words have been regularly entering the Oxford English Dictionary; indeed, some ("jungle", "bungalow", "pyjama") became mainstream generations ago.
The book Hobson-Jobson by Henry Yule and A.C. Burnell first published in 1886 gives a glossary of colloquial Anglo-Indian words.
While Indian English is often the butt of jokes by the "educated" British (eg, various works of literature from the colonial era, or Peter Sellers' brilliant portrayal of a socially-challenged Indian in The Party), recently Indian writers and writers of Indian origin, notably Salman Rushdie and Booker Prize winner Arundhati Roy, have been making more creative use of it in their works.
The distinct evolution of regional variations in contemporary usage has led to terminologies such as Hinglish (Hindi + English) and Tanglish (Tamil + English). These terminologies are often referred to in a humorous, self- deprecating way, but at times they also have a derogatory connotation with each region or strata of society having fun at the expense of others! Hinglish, Tanglish 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.