When a layer contains artwork, a disclosure triangle appears just to the left of the layer. Clicking this triangle reveals the contents of the layer within the Layers palette. Every object that appears in an Illustrator document appears listed in the Layers palette. The order in which items appear has significance—it indicates the stacking order, or object hierarchy of the file. Objects that appear at the bottom of the Layers palette are drawn first, and therefore they appear at the bottom of the object stacking order.

Clicking a disclosure triangle reveals the raw power of the Layers palette—the ability to view the entire object hierarchy of a file.

You can drag items listed in the Layers palette to adjust where they sit in the stacking order. Dragging an object from the bottom of the Layers palette to the top of the palette places that object at the top of the stacking order. It’s important to note that each layer and each group also maintain their own stacking order. The Layers palette basically represents the stacking order of the entire file.