Layers are amazingly powerful when it comes to drawing or editing images, especially if you want to add special effects to your picture. Knowing how to use the Layers palette to manipulate layers and their properties will allow you to spruce up your work immensely.
Take a look at the Layers palette (left). It's packed with lots of helpful shortcuts and functions. I've numbered the fourteen items visible in this image, though more icons appear when you start adding and manipulating layers.
1. Name of the layer. When you open an image, the layer that appears is automatically considered the background. Adding more layers stacks them on top of the background. The image that you see in the workspace window is the view from the top down, looking through all the layers as if they were sheets of plastic stacked on top of each other. If you only use one or two layers, you probably don't have to worry about what they are called in the palette. If you start editing images with multiple layers, though, you may want to rename each layer to describe the contents of the layer so that you can find it again easily. You can rename any layer (except the background) by double clicking on its name and typing the name you have chosen.
2. Layer thumbnail. This is a tiny picture showing the contents of the layer. The gray and white checkered pattern indicates that the layer is transparent, like a blank sheet of clear plastic.
3. "Link" box. The active layer, in addition to being highlighted in blue, will have a paintbrush in this box. For the non-active layers, if you click in this box, an icon of a chain will appear. This chain icon indicates that the layer is "linked" to the active layer. If you move the active layer, any linked layers move along with it. This is particularly helpful if you have an object in one layer and its shadow in another, for example, and you want to move both the object and the shadow together. You can "unlink" a linked layer by clicking on the chain, making it disappear.