Short for “picture element”, a pixel is one of many tiny, illuminated squares on a digital display. A smartphone screen contains thousands of pixels, so densely packed that they seem to disappear inside a smooth, vivid image. But packing pixels is necessary only for up-close viewing. A digital billboard can have fewer pixels than a smartphone yet still appear seamless from afar because the human eye can’t perceive individual pixels from great distances.
How Your Eyes Make Sense of the World.