Karachi is the capital city of the Pakistani province of Sindh. It is the largest city in Pakistan and 12th largest in the world, with a population of over 20 million. It is situated at the southern tip of the country along the Arabian Sea coast and formerly served as the country's capital from 1947 to 1959. Ranked as a beta-global city, it is Pakistan's premier industrial and financial centre, with an estimated GDP of over $200 billion (PPP) as of 2021. Karachi is a metropolitan city and is considered Pakistan's most cosmopolitan city, and among the country's most linguistically, ethnically, and religiously diverse regions, as well as one of the country's most progressive and socially liberal cities.