A bridge was the main command and control facility of a starship or a starbase. Commanding officers and first officers were often positioned on the bridge; officers whose duty were on the bridge were referred to as bridge officers.
Bridges featured a variety of consoles, as well as a viewscreen at the very front. On Federation starships, the tactical stations were often located on one side of the viewscreen while the flight controls were on the other side of the viewscreen, with both consoles having the main viewscreen facing forward. Also, very common in bridges of most species, were security, science and engineering consoles, where the science officers had access to the sensor readings, the security chiefs could see security breaches and the chief engineers could see any engineering problem on the ship.
Lyran Starfleet starships of heavy cruiser size or greater had two bridges by law. The first bridge was the standard bridge as understood by the Federation Starfleet and was called the navigation bridge, where the navigational equipment was located, while the second bridge, called the flag bridge, was the bridge from which a flag officer could command a fleet and contained communication consoles, as well as sensor consoles. Stoneship-class starships had the walls of both bridges built with red marble. (Star Trek: The Stoneship Files: "Highly Illogical")