Graphic Styles are using within Adobe Illustrator to retain the settings of the Appearance Panel.
A graphic style is a set of reusable appearance attributes. Graphic styles allow you to quickly change the look of an object; for example, you can change its fill and stroke color, alter its transparency, and apply effects in one step. All the changes you apply with graphic styles are completely reversible.
You can apply graphic styles to objects, groups, and layers. When you apply a graphic style to a group or layer, every object in the group or layer takes on the attributes of the graphic style. For example, assume you have a graphic style that consists of 50% opacity. If you apply the graphic style to a layer, all objects in or added to that layer will appear 50% opaque. However, if you move an object out of the layer, the object’s appearance reverts to its previous opacity.