and the hierarchical structure of the layers in a CNN. We will simplify the explanation by using an analogy. The analogy is a written document. In order to communicate through writing, we organize it as a series of paragraphs, which are composed of sentences, those sentences are composed of words, and the words of letters. So reading a document requires assessing the relationship of letters to one another in increasing layers of complexity, which is a kind of "deep" hierarchy, like the hierarchy in image analysis.