1. Alternatively referred to as a video display terminal (VDT) and video display unit (VDU),a monitor is a video display screen and the hard shell that holds it. In its most common usage, monitor refers only to devices that contain no electronic equipment other than what is essentially needed to display and adjust the characteristics of an image.
Like most TVs, the computer monitor has a CRT (Cathode Ray Tube) that is found inside the computer monitor as illustrated in the picture to the right. The CRT is the main component and most expensive part within your computer monitor.
Today, most users have replaced the traditional CRT monitor with the newer flat panel displays.
2. Monitor is a term to describe the process of viewing or watching over someone or something.