Illustrator stacks successively drawn objects, beginning with the first object drawn.
How objects are stacked determines how they display when they overlap. The stacking order of objects depends on the drawing mode you are using. When a new layer is created in the Draw Normal mode, it is placed right above the active layer and any new objects are drawn at the top of active layer. However, in the Draw Behind mode, when a new layer is created, it is placed right below the active layer and any new objects are drawn behind the selected object (or at the bottom of the active layer if no objects are selected).
You can change the stacking order (also called the painting order) of objects in your artwork at any time using either the Layers panel or Object > Arrange commands.
In the Draw Behind mode, select the object below which you want to add the new object.
In the Draw Normal mode, to add the new object to the top of a layer, click the name of the layer to make it active. In the Draw Behind mode, to add the new object to the bottom of a layer, click the name of the layer to make it active.
The artwork at the top of the Layers panel is at the front of the stacking order, while artwork at the bottom of the Layers panel is at the back of the stacking order. Within a layer, objects are also stacked hierarchically. By creating multiple layers in your artwork, you can control how overlapping objects are displayed.
Drag the item’s name and release the mouse button when black insertion marks appear in the desired position. Black insertion marks appear either between two other items in the panel or on the left and right edges of a layer or group. Items that are released over a layer or group are moved above all other objects in the item.
Click in the item’s selection column (between the target button and the scroll bar), drag the selection color box to a different item’s selection color box, and release the mouse button. If the item’s selection color box is dragged to an object, the item is moved above the object; if it’s dragged to a layer or group, the item is moved above all other objects in the layer or group.
To reverse the order of items in the Layers panel, hold down Ctrl (Windows) or Command (Mac OS) and click the names of the items whose order you want to reverse. The items must be at the same level in the layer hierarchy. For example, you can select two top-level layers, but you cannot select two paths that are in different layers. Then select Reverse Order from the Layers panel menu.
note: You cannot move a path, group, or collective element to the top position in the Layers panel—only layers can reside at the top of the layer hierarchy.
To move an object to the top or bottom position in its group or layer, select the object you want to move and choose Object > Arrange > Bring To Front or Object > Arrange > Send To Back.
To move an object by one object to the front or one object to the back of a stack, select the object you want to move, and choose Object > Arrange > Bring Forward or Object > Arrange > Send Backward.
For an example of how changing the stacking order in an illustration changes the design, see www.adobe.com/go/learn_ai_tutorials_depth_en. This tutorial is available only in English.