When you first import or scan an image into Photoshop Elements, it consists of just one default layer. In many cases, you'll find that you want to make just a few simple changes to your photo and will have no need for multiple layers. But when you begin working with some of the more involved and complex image manipulation and retouch tools, you'll find that layers can make things a whole lot easier.
Layers act like clear, transparent sheets stacked one on top of another, and yet, when you view a final image, they appear as one unified picture (Figure 5.1). As you copy and paste selections, you may notice that these operations automatically create new layers in your image. You can edit only one layer at a time, which allows you to select and modify specific parts of your photo without affecting the information on other layers. This is the real beauty of layers: the ability to work on and experiment with one part of your image while leaving the rest of it completely untouched. One exception to this is the adjustment layer, which lets you make color and tonal corrections to individual or multiple layers without changing the actual pixels.
Figure 5.1. Layers act like clear acetate sheets, where transparent areas let you see through to the layers below.
Layers appear in your image in the same order as they appear in the Layers palette. The top layer of your image is the first layer listed on the Layers palette, and the background layer is positioned at the bottom of the list (Figure 5.2).
Figure 5.2. By default, an image with layers consists of a background layer, with additional layers named Layer 1, Layer 2, and so on. But you can change the default names to more descriptive names at any time.