South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern part of the Korean Peninsula and borders North Korea along the Korean Demilitarized Zone; though it also claims the land border with China and Russia. The country's western border is formed by the Yellow Sea, while its eastern border is defined by the Sea of Japan. South Korea claims to be the sole legitimate government of the entire peninsula and adjacent islands. It has a population of 51.96 million, of which roughly half live in the Seoul Capital Area, the ninth most populous metropolitan area in the world. Other major cities include Incheon, Busan, and Daegu.

East Asia is a region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. Hong Kong and Macau, two coastal cities located in the south of China, are autonomous regions under Chinese sovereignty. The economies of Japan, South Korea, China, Taiwan, Hong Kong, and Macau are some of the world's largest and most prosperous economies. East Asia borders Siberia and the Russian Far East to the north, Southeast Asia to the south, South Asia to the southwest, and Central Asia to the west. To the east is the Pacific Ocean and to the southeast is Micronesia.