Aspect ratio

Aspect ratio is the proportion between the width and height dimensions of an element. This is particularly important with user-generated content, as people upload pictures of different sizes, and properly displaying them in a consistent way maintains visual harmony. Think of profile pictures on a social media site: they’re restricted to square or circular images, requiring users to resize or crop them.

The most common aspect ratios for images are 16:9 and 4:3, although 1:1 square images have grown in popularity thanks to sites like Instagram.