Short for Picture Element. The pixel is the smallest element that is used to build an image, whether it is displayed on a video screen, computer monitor, printed photo, or newspaper. A complete monitor image is made up of thousands of pixels. The pixel is often used as a unit of measurement for image size and resolution. The number of pixels (width and height) in an image defines its size, and the number of pixels in an inch (or other quantifiable measurement) defines the resolution of the image. The more pixels in an image the better its resolution.