A screen is composed of a large number of pixels, which determine its resolution. The higher the resolution, the more pixels it will have, and therefore, it will reproduce images with higher quality. A pixel on the screen or a dead pixel is when a pixel stops working. The size of a pixel is measured in millimeters, so it will go virtually unnoticed. When a pixel stops working, you may notice that one of the tiny dots on the screen appears defective, either not emitting light or emitting a permanent light of a different color (white, red, green, or blue). This will not affect the screen's resolution at all.