Because layers can sometimes overlap for design purposes, it is important to have control over their stacking order.
To rearrange layers, simply drag and drop them with the left mouse button from the Layers panel.
The layers from the bottom of the list will appear underneath the layers above them.
For example you can create a semi transparent dark colored layer and move it above a background image. This will create a darkening effect on the image.
This works in a smilar fashion as Adobe Photoshop’s layer system.