Basic Layer Types
Raster (or Pixel-Based) Layers – Generally, if no other designation is given, this is the type of layer you’re dealing with. Any layer that includes a photo or a non-vector drawing is a raster layer. The downside to these types of layers is that they don’t magnify well. That is, if you try to make them larger, they can look fuzzy or pixelated.
Type (or Text) Layers – When you select the text tool and start typing, Photoshop will automatically create a new layer and designate it as a type layer. These are easy to spot in the Layers panel, since they’ll include the symbol T. (See the diagram above for an example.) These layers are vector layers, so they can be scaled to any size without loss of quality.
Shape Layers – As with type layers, whenever you select any of the shape tools and start drawing a shape, Photoshop automatically creates a shape layer. These are vector layers as well.
Fill Layers – True to its name, a fill layer is one that is filled with a color, gradient or pattern. To add a layer of this type, you’ll need to select the Create new fill or adjustment layer tool at the bottom of the Layers panel (see diagram). Alternatively, you can select New Fill Layer from the Layer menu on Photoshop’s main tool bar.
Adjustment Layers – These layers allow you to modify the color, brightness, saturation, exposure and other features of an image without altering the original picture. They are created in the same manner as fill layers.
Smart Object Layers – As I mentioned earlier, one of the benefits of using a layered approach to build new images is that you are able to quickly modify one layer whenever you need to, instead of creating an entirely new image from scratch. Smart objects make this process even easier. When you convert a layer to a smart object layer, you can edit, export or replace the contents of that layer with just a couple of clicks.