Pixel is the smallest controllable element that makes up an image on a digital display. Each pixel can only display one color and together they blend to show different shades. Resolution refers to the sharpness of an image, measured by the number of pixels per inch (PPI). Higher resolutions like 4,000x2,700 pixels allow for clearer large prints without quality loss compared to low resolutions like 256x256 pixels. Aspect ratios describe the dimensional relationship between width and height of screens, images, or videos. Common aspect ratios include 4:3, 16:9, and 1.85:1.