Public Address Systems at a minimum comprises of a microphone, an amplifier and a loudspeaker.

Examples of content include announcements and other audio material at sports stadiums, air and rail terminals, and the sound produced by a singer, musician or musical ensemble, as well as recorded music.

A Public Address or PA System may include multiple microphones and/or other sound sources, a mixing console to combine and modify multiple sources, and multiple amplifiers and loudspeakers for louder volume, greater coverage and/or wider distribution, such as that required to provide sound throughout an entertainment venue, an office building or retail space, or an outdoor environment.