Drawing and painting in real life can be difficult. You might start with a pencil sketch, ink your lines, then add color over the top. This linear approach is nice because it is simple but difficult because it is inflexible and potentially destructive. If you need to go back and reference your pencil sketches, your lines might be covered with paint. If you painted a section with a color, it also might be difficult to change. These are the types of issues that layers can help with.
Layers are a way to organize all of the components of your artwork. One layer might have your rough sketches, while another layer might have your background. You could also have one layer with shadows and another with highlights. Layers are similar to painting on clear pieces of plastic. The separate pieces of plastic go over each other to build up the finished piece. The advantage is that you can modify one layer by itself without deleting or messing up other areas.
While layers are powerful, they are also dangerous. Too many layers can be a burden and slow down your computer. The more layers you have, the more time you will spend managing them. You spend more time organizing your layers and less time painting. Only you will be able to know where the balance is between what is helpful and what is a burden. Layers are all managed and organized through the Layers docker, so let’s start there.