A screen, also called a display screen, is an electrical appliance for displaying images and colors. The screen size is calculated based on the diagonal of the screen, usually in inch units. At present, the mainstream sizes are 17", 19", 21", 22", 24, 27", 32", etc. The length of the corner. The commonly used display screens have a screen (narrow screen) and a wide screen, and the screen has an aspect ratio of 4:3 (there is also a small ratio of 5:4), and the widescreen aspect ratio is 16:10 or 16:9. In the case of a constant diagonal length, the closer the aspect ratio is to 1, the larger the actual area. The wide screen is more in line with the shape of the human eye.