The main viewscreen is the large display at the front of a starship's bridge, showing the view outside the ship, tactical data and incoming communications.
The viewscreen is the centerpiece of most Starfleet bridges. It can magnify distant objects, display sensor readings and show the faces of people hailing the ship, which makes it the stage for countless first contacts and tense negotiations.
Designs changed over time, from the framed screen of the original Enterprise to the wide display of the Enterprise-D and the projected or transparent displays of later ships. Crews can switch it between forward, aft and other views, or turn it off entirely when needed.