Pixel is short for picture element. Basically it is a dot (actually a tiny square) on the computer screen. The dots are arranged in rows and columns and are so close together they appear to be connected. The dot can be a shade of gray or a color. A typical 1280 x 720 image has 921,600 pixels. The more dots that make up an image the better the resolution. A megapixel is simply one million pixels.