Photoshop filters let you change the look of your images, for instance giving them the
appearance of paintings or mosaic tiles, or adding unique
lighting or distortions.
In addition to filters, Photoshop also provides a variety of
effects—such as shadows, glows, bevels, overlays, and strokes—that let
you quickly change the appearance of a layer’s contents. Effects differ
from filters in that when you move or edit the contents of the layer, effects
change accordingly. For example, if you apply a drop shadow effect to a
text layer, the shadow changes automatically when you edit the text.
Effects that you apply to a layer become part of the layer’s custom layer
style. When a layer has a layer style, an “f” icon appears to the right of the
layer’s name in the Layers palette. You can expand the layer style in the
Layers palette to view all the effects used in the layer style and edit the
effects to change the layer style.
When you save a custom layer style, it becomes a preset layer style.
Preset layer styles appear in the Styles palette and can be applied with
just a click of the mouse. Photoshop provides a variety of preset styles to
fill a wide range of uses.
Layer styles let you quickly apply effects to a layer’s content. You can
scan through a variety of predefined layer styles and apply a style with just
a click of the mouse, or you can create a custom style by applying multiple
effects to a layer.
Note: You cannot apply layer effects and styles to a background, a locked
layer, or a layer group