Using appearance attributes
You can apply appearance attributes to any object, group, or layer by using effects and the Appearance and Styles palettes. An appearance attribute is a property—such as a fill, stroke, transparency, or effect—that affects the look of an object, but does not affect its basic structure. An appearance attribute can be changed or removed at any time without changing the underlying object or any other attributes applied to the object.
The advantage to using the Appearance palette to add effects or other attributes is that they can be selected and edited at any time.
For example, if you apply a drop shadow effect to an object, at any time you can change the drop shadow distance, blur, or color. You can also copy that effect ...