Layers are an essential part of Photoshop; using them effectively will help organize the workspace and create powerful images.
Photoshop layers are like sheets of stacked paper.
You can see through transparent areas of a layer to the layers below
CREATE a new layer, click the New Layer Icon, or select Layer > New > Layer.
COPY a layer, drag and drop the layer onto New Layer Icon, or Right-click and select Duplicate Layer.
DELETE a layer, select the layer and click the Delete Layer (trash can) icon.
To rearrange the layer order, drag the layer to the appropriate order in the stack, using the thick black line that appears between the stacks as your guide.
Each layer can be hidden temporarily from view by clicking Visibility (eye icon) in the Show/Hide column of the Layers palette.
To rename a layer, double-click the current layer name. Type in the layer name and click OK.
To group layers, select the Folder Icon then drag and drop layers into or out of the new group.
By default, the background layer in a new document is locked.
To unlock this layer, click the Padlock icon on the background layer.
There are fIve locking options found on the Layers palette; each of them will have different locking effects on the image.
Lock transparent pixels — Lock the transparent areas of the layer and only the areas with content can be edited or changed.
Lock image pixels — Lock areas of the layer with image content and only areas with transparency can be edited or changed.
Lock position — Lock the position of the layer but still allow for edits or apply effects to the content of the layer.
Prevent Auto Nesting into and out of artboard.
Lock all — Lock the entire layer and not allow layer contents to be edited or moved.
Layers can be linked together so that they can be transformed and moved at one time.
To link layers, select two or more layers, then click Link.
To unlink the layers, select the linked layers and click Link again.
When finished editing or creating an image Photoshop enables layers to be merged and flattened in order to reduce file size. Access through the Drop Down Layer menu.
Merge Down will merge the active layer with the layers below
Merge Visible will merge all visible layers in your document and leave hidden layers on their own.
Flatten Image will merge all your layers together.
Blending Modes let you determine how colors in the upper layer blend with the colors in the lower layer.
Some of the more commonly used blend modes are Multiply, Screen, Overlay and Soft Light.