Mumbai, formerly known as Bombay, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fifth most populous city in the world, with a population of approximately 12.5 million. Along with the neighboring urban areas, including the cities of Navi Mumbai and Thane, it is one of the most populous urban regions in the world. Mumbai lies on the west coast of India and has a deep natural harbor. As of 2009, Mumbai was named an Alpha world city. Mumbai is also the richest city in India, and has the highest GDP of any city in South, West or Central Asia.
Mumbai is the commercial and entertainment capital of India, generating 5% of India's GDP, and accounting for 25% of industrial output, 70% of maritime trade in India (Mumbai Port Trust & JNPT), and 70% of capital transactions to India's economy. Mumbai is home to important financial institutions such as the Reserve Bank of India, the Bombay Stock Exchange, the National Stock Exchange of India and the corporate headquarters of numerous Indian companies and multinational corporations. It houses some of India's premier scientific and nuclear institutes like BARC, NPCL, IREL, TIFR, AERB, AECI, and the Department of Atomic Energy. The city also houses India's Hindi (Bollywood) and Marathi film and television industry. Mumbai's business opportunities, as well as its potential to offer a higher standard of living, attract migrants from all over India and, in turn, make the city a potpourri of many communities and cultures.