Layer blending modes are a key part of the Photoshop program. When you have more than 1 layer, than you can blend the layers together. The blending modes are broken into 6 main areas. 1). Basic, 2). Darken, 3). Lighten, 4). Contrast, 5). Comparative, and 6). Composite. Instead of this being a tutorial, this is going to be more of a reference guide. Keep our website as a favorite and refer back to this document whenever you are trying to blend layers.