Abstract: A display device includes: a housing that has a space formed therein, the space opening at two end faces that are opposed to each other; two lenses that are placed in the space; and a display part that has a display panel and is placed on the side of one of the two end faces. The display part can be switched between a first state in which the display panel is exposed to the exterior of the housing and a second state in which the display panel faces toward the interior of the housing.

Abstract: An image display device is provided with: a data obtaining unit that obtains data from a server via a communication network; a display unit; a display control unit that controls image display in the display unit; a position and orientation determining unit that determines a position change and an orientation of the image display device; a position-related information generating unit that generates and transmits information related to a position and an orientation based on the determination result; and a position-related information obtaining unit that obtains information related to a position and an orientation transmitted from another image display device, wherein the display control unit causes the display unit to display an image based on the data obtained from the server and adapts the image based on the determination result of the position and orientation determining unit, and further causes the display unit, based on the information related to a position and an orientation transmitted from the another i