The Visiograph was a piece of communications technology in use by the Space Rangers and the Office of Space Affairs on Earth. All of their outposts and spacecraft were equipped with the device. It consisted of a video screen which could be used to view distant locations, space or even "tuned-in" to the interiors of buildings to watch goings-on within. The Visiograph could also be used for "face-to-face" communication if both parties had a screen.