Create Adjustment Layers for Nondestructive Changes
Photoshop Elements is pixel-editing software, designed to work with the pixels of a digital image. This is what you have been doing in the book so far except for your work with the Smart Brush in task #45. One problem with working directly on the pixels of an image is that every time they are changed, there is the potential for the loss of image quality as the pixel data changes. The pixels cannot gain more information, but they can lose it.
You can work on your image without changing any pixels by using adjustment layers and layer masks. Adjustment layers give you a huge range of flexibility and power that you do not get when working directly on the pixels of an image. The interface ...