What is Cyworld, exactly? It's an Internet service that lets people create their own home pages -- pages that can accommodate an unlimited numbers of photos, documents, and other goodies. It's similar to U.S. social networking sites such as MySpace or The Facebook, but with extra twists that make it more realistic and alluring. Home pages, for example, appear three-dimensional. Users decorate their "rooms" with digital furniture, art, TVs, even music. Since avatars stop by, the idea is to make your space as cool as possible. Instant messaging is included in the service, so you can chat with visitors. You can even enter Cyworld from a mobile phone.