Aspect ratio

A film or video frame’s width-to-height ratio on any viewing screen. Standard-definition (SD) video (used for older TV screens) has an aspect ratio of 4:3. High-definition (HD) video has an aspect ratio of 16:9. Social media platforms and websites allow for, and sometimes require, video clips with a variety of aspect ratios such as square (1:1) or vertical (for example, 4:5 or 9:16).