Aspect ratios describe the proportional relationship between the width and height of an image or screen. It is expressed as two numbers separated by a colon, such as 16:9 or 4:3. The first number represents the width, while the second indicates the height. This ratio helps determine how content is displayed, whether on a television, computer monitor, or in photography. Different aspect ratios serve various purposes. For example, 16:9 is commonly used for high-definition television and video, providing a widescreen format. In contrast, 4:3 was standard for older televisions and some computer screens. Understanding aspect ratios is essential for creating visually appealing content.