Delhi officially the National Capital Territory of Delhi (NCT), is a city and a union territory of India.It is bordered by Haryana on three sides and by Uttar Pradesh to the east. It is the most expansive city in India—about 1,484 square kilometres (573 sq mi).
It has a population of about 25 million, making it the second most populous city after Mumbai and most populous urban agglomeration in India and 3rd largest urban area in the world.
Urban expansion in Delhi has caused it to grow beyond the NCT to incorporate towns in neighbouring states. At its largest extent, there is a population of about 25 million residents as of 2014.After Mumbai, Delhi has the second-highest number of billionaires and millionaires in India.