A conceptual model is an explanation, usually highly simplified, of how something works. It doesn't have to be complete or even accurate as long as it is useful. The files, folders, and icons you see displayed on a computer screen help people create the conceptual model of documents and folders inside the computer, or of apps or applications on the screen. In fact, there are no folders inside the computer ─ those are effective conceptualizations designed to make them easier to use. Sometimes these depictions can add to the confusion, however. When reading email or visiting a website, the material appears to be on the device, for that is where it is displayed and used. But in fact, in many cases the actual material is "in the cloud," located on some distant machine. The conceptual model is of one, coherent image, whereas it may actually consist of parts, each located on different machines that could be almost anywhere in the world.