Seoul, the capital of South Korea, has been called by a number of formal and informal names over time.

Seoul, officially Seoul Special City, is the capital of the Republic of Korea (ROK), commonly known as South Korea, and the country's most extensive urban center. The broader Seoul Capital Area, encompassing Gyeonggi province and Incheon metropolitan city, emerged as the world's fourth largest metropolitan economy in 2014, trailing only Tokyo, New York City, and Los Angeles, hosting more than half of South Korea's population. Although Seoul's population peaked at slightly over 10 million, it has gradually decreased since 2014, standing at approximately 9.97 million residents as of 2020. Seoul is the seat of the South Korean government.