The Concept of Layers in Photoshop Elements
By David Asch
"The concept of layers can be a tricky thing to get to grips with; we are, after all, used to creating artwork on the more traditional mediums of paper or canvas, where everything takes place on a single surface. This is unforgiving when it comes to versatility, however. If we make a mistake it’s usually irrevocable and we either have to start again, or cover up the error in some other way.