Layers are the bedrock of successful image editing in Photoshop. You can imagine Photoshop layers as separate sheets of clear acetate, hovering over your background image. By using layers it's possible to make all manner of changes to the picture, without affecting one single pixel on the original background image.
When you open a digital image in Photoshop, it contains only one layer; the Background layer. In Photoshop, layers are held in the Layers palette and stack one on top of the other. Whenever you copy and paste image data into a file in Photoshop, the new image component is placed on its own separate layer, which you can move, edit, manipulate, and resize to your heart's content. The usefulness of layers does not stop there; each layer can interact with the ones below it in the Layers palette, via blending modes, providing almost unlimited creative possibilities.
Add to this the fact that the opacity of a layer can be modified between fully opaque and semi-transparent, and it's easy to see why layers are so important to digital image manipulation.
Layers can also be moved and resized independently of each other. The key to moving layers is the Move tool. This tool, located in the top right of the Toolbar, can be used to drag an entire layer—and consequently the image elements on that layer—into a new position within the image. This repositioning ...