At first glance, layers might seem complex, but the idea is really rather simple: You isolate different parts of an image onto independent layers so that you can work with them separately. Think of each layer as a piece of glass, with the individual layers stacked on top of each other as if they were separate documents (Figure 3.1). By putting each image on its own layer, you can change your document’s look and layout freely without committing to the changes. If you paint, apply a filter, or make an adjustment, it affects only the layer on which you’re working. If you get into a snarl over a particularly troublesome layer, just throw it away and start over. The rest of your document will remain untouched—safe and handy!