A network system includes a directory server configured to provide service definition information through a network, and a terminal device configured to receive the service definition information. The directory server may include a server communication unit, a service definition information storing unit configured to store main information and auxiliary information as part of service definition information, and a service definition information transmission control unit that retrieves the service definition information from the service definition information storing unit and transmit the same to the terminal device. The terminal device may include a terminal communication unit, an outputting unit, an input receiving unit and an output control unit. When received the service definition information from the directory server, the output control unit controls the outputting unit to output the main information, and when the input receiving unit receives a predetermined input instruction, the auxiliary information is output.