A head-mounted display includes a display section that displays a display image, a communication section that communicates with a client apparatus and an external server system, and a processing section, the communication section receiving an HTTP request when the client apparatus has displayed an operation screen on a display section of the client apparatus, and transmitted the HTTP request to the head-mounted display based on an operation performed using the operation screen, the processing section executing a command that corresponds to the HTTP request, and the communication section transmitting an execution result of the command to the client apparatus as an HTTP response.