The public address system was an electronic amplification system used for making announcements in a large public area, in a building, or in a starship.
In the 2250s, announcements for crewmembers or teams on the USS Discovery were made through this system. (DIS: "Context Is for Kings") This system remained intact and functional after the Discovery's retrofit in 3189. (DIS: "Unification III")
Closed captioning identified the system with the abbreviation "PA".