About layer styles

Layer styles allow you to apply effects--such as drop shadows and bevels--to a layer's content. The boundaries of the effect are automatically updated when you edit that layer. For example, if you apply a drop shadow style to a text layer, the shadow will change automatically when you edit the text.

Layer styles are cumulative, which means that you can create a complex effect by applying multiple styles to a layer. You can also change a layer's style settings to adjust the final effect.

Using Layers > Using layer styles > About layer styles