Each document includes at least one named layer. By using multiple layers, you can create and edit specific areas or kinds of content in your document without affecting other areas or kinds of content. For example, if your document prints slowly because it contains many large graphics, you can use one layer for just the text in your document; then, when it’s time to proofread the text, you can hide all other layers and quickly print the text layer only. You can also use layers to display alternate design ideas for the same layout, or versions of advertisements for different regions.
Think of layers as transparent sheets stacked on top of each other. If a layer doesn’t have objects on it, you can see through it to any objects on layers behind it.
Additional layer notes: