The basics of layers

Photoshop, and many other photo editing tools, are based around the concept of layers. Yes, you can do basic tasks in Photoshop without knowing about layers, but to do anything more involved that cropping and rotating pictures, it helps to have an understanding of layers.

Think of layers as sheets of paper. Paper comes in different weights. The 36-lb sheet of paper can be considered an opaque layer. A 10-lb sheet of paper (does that exist?) can be thought of a a semi-transparent layer. A sheet of tracing paper can be thought of as a transparent layer.

The final image in Photoshop is what you see after stacking all your sheets of paper, or layers, on top of each other. You can control the order the layers are in, and that order can make a huge difference in the final image.