What does 'aspect ratio' refer to?

Aspect ratio refers to the relationship between the width and height of an image or video. It is expressed as two numbers separated by a colon, with the first number representing the width and the second number representing the height. For example, an aspect ratio of 16:9 means that for every 16 units of width, there are 9 units of height. Understanding aspect ratio is essential in digital photography and videography, as it affects how the image is framed and displayed on various screens and mediums. Different aspect ratios can convey different artistic or compositional effects, impacting how viewers perceive the content.