Answer: Digital product illustrations and other graphical elements are usually set up in layers. Designers want the original file so that they can make changes to one or more elements in the document without affecting the rest of it.

For example, let's say you have base art, such as a photograph, along with other elements, such as text or a logo. If these elements overlap, they each constitute an individual layer. The base art is one layer, and the text and logo make up the other two layers.