The main reason for doing this is to minimize the destructive nature of some of the things we do in Photoshop. “Destructive” may seem like a harsh term when we are, in fact, making the image better. What the term really refers to is the fact that original pixel data is being replaced by something else. After that happens, it may not be possible to undo the change especially if you work in an infographic company. This may come as a surprise, but any retouching tool that samples pixel data from one part of the image and paints it into another part of the image is destructive by its very nature because pixels are being permanently altered.

After those tools have been used and the image has been closed, those changes can’t be undone. Therefore, you must learn various retouching strategies that protect the original properties of the underlying image. The most fundamental way of accomplishing this is to duplicate the layer that’s being retouched — quite often the Background layer—and doing all retouching on it instead of the original layer.