Hong Kong is a special administrative region of China. Situated on China's southern coast just south of Shenzhen, it consists of Hong Kong Island, Kowloon, and the New Territories. With 7.5 million residents in a 1,114-square-kilometre (430 sq mi) territory, Hong Kong is the fourth-most densely populated region in the world.Hong Kong is a highly developed territory and has a Human Development Index (HDI) of 0.955, ranking eighth in the world and currently the only place in Asia to be in the top ten. The city has the highest life expectancy in the world, and a public transport usage exceeding 90 per cent.