Overlays are subtle colored layers applied to images, creating a veil that can be lighter or darker. Their main purpose is often to reduce the prominence of an image, allowing it to blend better with its surroundings or other visual elements. This effect is frequently seen when a specific image needs focus, while others on the same screen should be less eye-catching.

In addition to modifying an image's prominence, overlays are also handy tools for improving text readability. When text is placed over an image, an overlay can serve as a background, enhancing the contrast between the text and the underlying image. This ensures that users can easily read the text without distraction, making overlays a versatile and valuable tool in design.