South Korea profile
South Korea has developed into one of Asia's most affluent countries since partition in 1948. The Communist North has slipped into totalitarianism and poverty.
The Republic of Korea was proclaimed in August 1948 and received UN-backed support from the US after it was invaded by the North two years later.
The Korean War ended in 1953 without a peace agreement, leaving South Korea technically at war for more than fifty years.
The following four decades were marked by authoritarian rule. Government-sponsored schemes encouraged the growth of family-owned industrial conglomerates, known as "chaebol". Foremost among them were the Hyundai and Samsung groups.
They helped transform South Korea into one of the world's major economies and a leading exporter of cars and electronic goods.
South Korea is one of the Asian Tigers along with Hong Kong, Singapore and Taiwan which have free and highly developed economies which grew rapidly between the 1960s and the 1990s.
A multi-party political system was restored in 1987.
Relations with its northern neighbour remain a major concern in Seoul, particularly over the North's fragile economy and its nuclear ambitions. South Korea generally resisted international calls for sanctions against the North over its nuclear programme and pursued a "sunshine" policy of engagement in the late 1990s.
This involved aid - including shipments of fertiliser and rice - reunions between North and South Koreans, tourist projects and economic cooperation. South Korean companies employed thousands of North Korean workers at the Kaesong industrial complex near the border.
The "sunshine" ended with the election in 2008 of conservative President Lee Myung-bak, who adopted a tougher tone towards the North in response to its failure to move on the nuclear issue.
Tensions were heightened further by a spate of Northern missile tests in 2009 and then by the sinking of the Southern naval ship Cheonan in March 2010, in which 46 sailors died.
After international investigators reported finding evidence that the Cheonan was sunk by a torpedo from a North Korean submarine, South Korea stopped all trade between the two states. Pyongyang rejected the claim as "fabrication" and retaliated by cutting all relations with Seoul.
A serious cross-border clash in November 2010, as a result of which the South Korean military was placed on its highest non-wartime alert. After a North Korean long-range missile test in April 2012, the South reached agreement with the US to nearly triple the range of its ballistic missile system to 800 km.
The demilitarised zone (DMZ) between South and North Korea is the world's most heavily-fortified frontier.
The US has tens of thousands of soldiers in South Korea and has operational control over South Korean troops in the event of war. Seoul was due to resume control in 2015, but appears to want an extension, given ongoing tensions with the North.