What is Monitor?
A video monitor or video display unit (VDU) or video display terminal(VDT), makes it possible for a computer user to see input character as they are typed, but it also serves as an output device for receiving messages from the computer.
Images on a monitor are composed of tiny dots, called pixels(for picture elements). A squire inch of an image on a typical monitor is a grid about 72pixels on each side. Such a monitor is said to have a resolution of 72dots per inch(dpi). The higher the resolution the together the dots.
Also, Checkout this article: