A visual isplay unit, often called simply a monitor or display, is a piece of electrical equipment which displays images generated from the video output of devices such as computers without producing a permanent record. A newer monitor typically consists of a TFT LCD, with most older monitors based around a cathode ray tube (CRT.) The monitor comprises the display device, simple circuitry to generate and format a picture from video sent by the signals source, and usually an enclosure. Within the signal source, either as an integral section or a modular component, there is a display adapter to generate video in a format compatible with the monitor.