Korea, Republic of

South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and the Sea of Japan to the east. South Korea claims to be the sole legitimate government of the entire peninsula and adjacent islands. It has a population of about 52 million, of which half live in the Seoul metropolitan area, the ninth most populous metropolitan area in the world, with other major cities being Busan, Daegu, and Incheon.