Layers are used in Photoshop for organizing design elements in a composition.
Layers can be thought of as separate sheets of acetate laid one over another, each displaying some part of the composition. Design elements on separate layers can be edited individually without effecting elements on other layers. This allows for flexibility in composing and revising an image.
New files are created with a background layer. Background layers are the very bottom most layers and other layers cannot be placed beneath them. Background layers do not allow for transparency. Layers can be added above the background layer.
To convert a background layer to a layer which will be transparent and which can be rearranged in the stacking order, double click on the background layer. A New Layer window appears. At this point, name the layer and click ok. Background layer is now converted.
“Stacking order” refers to the order in which Photoshop layers are arranged. Whatever image is in the topmost layer will be viewed on top of the other images in the other layers. The bottom most layer (usually background) is seen at the bottom of the stack and will show through the transparent areas of subsequent layers. The order of a layer can be rearranged by clicking on that layer and dragging and dropping it where you want it in the stacking order. This is one simple way to arrange design elements in a composition.
Layers can be viewed or made invisible by turning on or off the eye icon to the left of the thumbnail for each layer.
CREATING LAYERS
Layers can be created one of several ways:
LINKING LAYERS
Layers can be linked and moved simultaneously. Linked layers can be transformed together. To link a layer, select the layer, then click on the box to the right of the “eye” icon on the other layer you wish to link to it. A linking icon will appear. Transform or move as you desire.
DUPLICATING LAYERS
There are several ways to copy or duplicate a layer:
DELETING LAYERS
There are several ways to delete a layer. If you have deleted a layer and immediately change your mind, Ctrl/Command + Z to get it back. Using the history palette will also allow you to reclaim the layer that was deleted if the file is still open and has not been saved and closed.