What is one characteristic of fill opacity in comparison to overall opacity?

Fill opacity specifically controls the transparency of a layer's contents without altering the opacity of any layer effects applied to that layer, such as drop shadows or glows. This characteristic is crucial for designers who want to maintain the visibility of effects while adjusting the transparency of the actual content.

For instance, if you have a layer with an image and a drop shadow applied, reducing the fill opacity will make the image more transparent but will leave the shadow fully visible. This feature allows for greater flexibility in compositing and visual design. Overall opacity, in contrast, affects both the contents and the layer effects equally, diminishing their visibility together. Thus, fill opacity allows for nuanced control separate from the overall appearance of the layer.