The aspect ratio of an image is the ratio of its width to its height. It is expressed as two numbers separated by a colon, in the format width:height. Common aspect ratios are 1.85:1 and 2.39:1 in cinematography, 4:3 (originally) and 16:9 in television, and 3:2 in still photography. Other common display aspect ratios include 5:4 and 16:10. The 1:1 aspect ratio is used for square images, often seen on social media platforms like Instagram, and 21:9 is an "ultrawide" aspect ratio popular for gaming and desktop monitors.