The Seoul Capital Area or Gyeonggi region, is the metropolitan area of Seoul, Incheon, and Gyeonggi Province, located in north-west South Korea. Its population of 26 million is ranked as the fourth largest metropolitan area in the world. Its area is about 12,685 km2 (4,898 sq mi). It forms the cultural, commercial, financial, industrial, and residential center of South Korea. The largest city is Seoul, with a population of approximately 10 million people, followed by Incheon, with 3 million inhabitants.

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.