Layer styles are applied to the layers in the active document. When you add a style to a layer, the results of the style are only displayed in that layer. Each layer can have it's own style, and you can apply more than one style to a single layer. Layer styles can be applied to any layer, except the Background.
Two of Photoshop's layer styles require transparent and non-transparent layer elements (Drop Shadow and Outer Glow). For example, to apply a Drop Shadow to a layer, it would require a transparent area within the image to hold the shadow.
Layer Styles |