South Korea’s most popular social networking site, Cyworld, has now brought a version of its site to the US. Founded in 1999, Cyworld was bought in 2003 by SK Telecom, Korea’s primary provider of mobile telecommunications. Since then Cyworld has experienced rapid growth, becoming a social networking phenomenon in South Korea. In fact, Cyworld has claimed more than one third of Korea’s entire population as members, while achieving incredible penetration of Korea’s young adult market: 90% of Koreans in their 20s are members of Cyworld.

Cyworld - US version - lets users sign up and create their own profile (called a Minihome in Cyworld) and their own avatar (Minime) for free. You can then personalize your avatar, design a Miniroom, meet new people, stay in touch with friends, send messages, upload photos, exchange gifts, and more. Essentially, Cyworld allows users to create their own personalized cyber-lives through which they can live vicariously, express themselves, and connect with friends.

The company has recently expanded its social networking site to other countries including China, Taiwan, Japan, and now the US. It is sure to face steep competition from US social networking giants MySpace and Facebook, and will face difficulty luring away US users who have been long-entrenched in their familiar social networks. It will be interesting to see whether Cyworld’s great success in Asia can translate to success in the US.