Aspect ratio refers to the proportional relationship between the width and height of an image or screen. It is usually expressed as two numbers separated by a colon, such as 16:9 or 4:3. The first number represents the width, while the second number represents the height. This ratio helps determine how an image or video will fit on different displays, ensuring that it appears correctly without distortion. Different aspect ratios are used for various media. For example, television screens often use a 16:9 aspect ratio, which is ideal for high-definition video, while older televisions might use a 4:3 ratio. Understanding aspect ratio is essential for content creators and consumers alike, as it affects how visual content is experienced.