The monitor or display is the standard output receiver. Without a monitor, the video card's information would not be seen. Monitors, like TV screens, use cathode ray tubes (CRT). I will now link you into some other sites for more information.

Webopedia Monitor http://aol.pcwebopedia.com/TERM/m/monitor.html

Tech Web Tech Encyclopedia Monitor http://www.techweb.com/encyclopedia/defineterm?term=monitor