The monitor is the peripheral device, in the case of a PC or desktop computer, or built-in device, in the case of a portable computer, that includes the screen on which data can be displayed. Until not so long ago, the typical monitor attached to a home computer was a CRT or Cathode Ray Tube, a vacuum tube that produces light when energized by the electron beam generated inside it. A heated cathode and grids in the neck of the tube make up each "gun" and the some CRTs (such as televisions) have three guns, one each for red, blue and green colours. Electrons are accelerated from the gun toward the front surface of the tube - or 'screen' and produce a beam. The surface on the back of the screen is coated with phosphors that light up when struck by the electron beam. Nowadays, a new type of monitor is catching on fast - the TFT or Thin Film Transistor - a flat type of LCD (Liquid Crystal Display) panel display screen in which each pixel is controlled by one to four transistors. TFT technology provides excellent resolution but it is also relatively expensive. TFT screens are sometimes called "Active Matrix LCDs". See here for explanations of the terms pixel and resolution. | 
