Hong Kong, formally the Hong Kong Special Administrative Territory of the People's Republic of China (HKSAR), is a Chinese city and special administrative region in South China's Pearl River Delta. Hong Kong is one of the most densely populated locations in the world, with 7.5 million citizens of diverse nationalities living in a 1,104-square-kilometer (426-square-mile) area. Hong Kong is also one of the world's three major financial centers and one of the most developed cities.
Hong Kong became a British Empire territory when the Qing Empire surrendered Hong Kong Island to Xin'an County at the conclusion of the First Opium War in 1841, then again in 1842. Following the Second Opium War, the colony was expanded to the Kowloon Peninsula in 1860 and was further extended when Britain won a 99-year lease of the New Territories in 1898. During World War II, Imperial Japan controlled British Hong Kong from 1941 to 1945; British rule was restored after Japan's defeat. In 1997, China took over the whole area. Hong Kong, one of China's two special administrative areas (the other being Macau), maintains distinct governance and economic systems from mainland China in accordance with the premise of "one nation, two systems."
Originally a thinly inhabited region of agricultural and fishing towns, the territory has grown to become one of the world's most important financial and commercial hubs. It is the tenth-largest exporter and ninth-largest importer in the world. Hong Kong has a large capitalist service economy with minimal taxes and free trade, and its currency, the Hong Kong dollar, is the world's eighth most traded currency. Hong Kong has the world's third-highest concentration of billionaires, the second-highest concentration of billionaires in Asia, and the world's greatest concentration of ultra-high-net-worth people. Despite having one of the greatest per capita incomes in the world, the city has considerable income disparity among its residents.
Hong Kong is a developed territory that ranks fourth on the United Nations Human Development Index. The metropolis boasts the most skyscrapers of any city in the world, and its citizens enjoy among of the world's greatest life expectancies. The dense population has resulted in a highly developed transportation network, with public transit rates reaching 90%. The Global Financial Centres Index places Hong Kong third.