Seoul, officially the Seoul Special City, is the capital and largest metropolis of South Korea. A megacity with a population of over 10 million, it is the largest city proper in the OECD developed world.[6] The Seoul National Capital Area is the world's second largest metropolitan area with over 25 million[7] inhabitants, which includes the surrounding Incheon metropolis and Gyeonggi province. Almost a quarter of South Koreans live in Seoul, half of South Koreans live in the metropolitan area, along with over 275,000 international residents.