When pitching your design to a consumer, presentation is always crucial. Showing a clean and polished design at any stage of the design process is a powerful way to convince your buyers that what you are offering is worth buying. "the mockup is typically a mid- to high-fidelity representation of the product’s appearance, and shows the basics of its functionality. Mockups fill in the visual details (such as colors, typography, etc.) and are usually static. By looking at a mockup, you should get a good idea of how the final product will look and a rough idea of how it might function (even if the functions aren’t yet working). A mockup can be considered a high-profile visual design draft." - "Cheap Mockups." - "Professional quality."