Abstract: A method of managing multiple content servers to provide a portal service is provided. Personal information on a user managed by the portal service is mutually used by a plurality of content servers to authenticate or identify the user. The content servers use an ID of a set-top box and an integrated ID of the user transmitted from the set-top box so as to identify a particular user and a set-top box of the user among users provided with a plurality of services.

Abstract: Provided is an apparatus for providing a service that links closed user groups (CUGs) based on a smart TV and a smart set-top box. A server may provide at least one application (app) store: The app store may register apps provided by developers, and may provide the registered apps to users of a CUG. The app retriever may provide a result of inquiry and retrieval performed with respect to apps registered in the at least one app store, to a terminal that performs the inquiry and retrieval. The terminal distributed for a predetermined CUG service may use apps associated with varied CUG services through the server.