A transportable recording medium includes an area for storing encrypted cookie information. The same cookie information is thus easy to use in different terminals and the cookie information becomes unique to respective users instead of respective terminals. A Web site reads the encrypted cookie information, decrypts the encrypted cookie information using a secret key stored in the Web site, customizes a requested service according to the decrypted cookie information, and provides the customized service to a terminal. If the Web site stores non-encrypted user information, the recording medium stores a media identification. The Web site stores the user information so that the user information of the user assigned to the recording medium is searched for according to the media identification. The Web site reads the media identification from the recording medium, searches for user information corresponding to the media identification, and customizes a requested service according to the user information.