A layer in a piece of digital art is a magical thing that can make our workflow smoother and easier, and can also save a lot of headaches in the future when we go from pencils to inks to colors. Okay, so maybe it's not actually magic. But it's pretty darn close!
But what is a layer and how do they work? Let's look at the following example image. The drawing in this screenshot is made from five layers:
What exactly are those layers? In the following screenshot, we can see exactly what they are:
The white background is a paper layer. Then, there is a layer of the base flat colors for each part of the drawing. Above that is a layer of shading and highlights. Then, above that in the stack, is the actual line art (inks) for the character and the motorcycle. Finally, above all the other layers is the text for the cover.
Think of layers like a stack...