The mix-blend-mode: difference; CSS property is one of the blending modes available in CSS for combining the colors of an element with its backdrop. This blend mode compares the colors of the element and its backdrop, subtracting the background color from the foreground color or vice versa, depending on which has the higher value for each color channel (red, green, blue).

Here's how the difference blend mode works:

1. Comparison of Colors: For each pixel in the element and its backdrop, the color values are compared channel by channel (red, green, blue).
2. Subtraction: If the color value of the element is greater than the corresponding color value of the backdrop, the backdrop's color value is subtracted from the element's color value. If the backdrop's color value is greater, the element's color value is subtracted from the backdrop's color value.
3. Resulting Color: The resulting color after the subtraction is used as the final color for that pixel.
4. Inversion: Additionally, if the result of the subtraction is negative, it is then inverted (turned into its positive equivalent) to ensure the resulting color is valid.
5. Visual Effect: The difference blend mode often produces an effect where areas of similar color between the element and its backdrop tend to become darker, while areas of contrasting color become lighter or more vivid.
6. Usage: You can apply the difference blend mode to an element using the mix-blend-mode property in CSS. For example:
   

 .element {

mix-blend-mode : difference;

}

Overall, the difference blend mode can be useful for creating visual effects such as negative-like images, emphasizing contrasts between elements and their backgrounds, or for creative design purposes. However, it's important to experiment with this blend mode to achieve the desired effect and consider its impact on the overall design aesthetics and user experience.