Viewers or monitors were the optical and visual devices and screens used aboard starships, such as viewscreens and scopes. "Viewer" was a general term for equipment found among numerous races. Viewers came in a variety of sizes, from desktop units to wall-mounted versions such as those commonly found on the main bridge of a starship. Some viewers were equipped to generate three-dimensional images. (TOS: "Where No Man Has Gone Before")
A bridge control monitor allowed for viewing and changing starship bridge controls. (TOS: "And the Children Shall Lead")
Viewers were also found in bars and restaurants such as in the Café des Artistes in Paris on Earth. (TNG: "We'll Always Have Paris")
NX-class starships also featured viewers in the ship's galley and in the pantry. (ENT: "The Catwalk")
