"Prototype is one of those words that can mean something different to everyone. Before I get too far along in a discussion of prototyping, it's probably worth exploring what I'm talking about. In the world of designing interactive products and services, prototype is generally defined as some representation of a design idea. In the world of physical products, the term tends to connote something quite similar to the finished manufactured form. Indeed, industrial designers use the term model to describe what interaction designers think of as a prototype.
Nomenclature aside, this process of representing the product that will ultimately be created is a core design activity. Henry Dreyfuss, one of the fathers of industrial design, gave much consideration to this activity in his classic book, Designing for People:
"Too much emphasis cannot be placed on the importance of three-dimensional models... When our ideas have been formulated, we design in clay, then plaster, finally in a material that will simulate the material to be used in manufacturing the actual product." (Henry Dreyfuss, Designing for People, pp. 61–62.)
In the broadest sense, all kinds of design artifacts are prototypes. Pencil sketches, blocks of wood, storyboards, wireframes, foam-core models, pixel-perfect state renderings, clickable demos, and functioning production code are all strategies for representing a thing being designed. However, in the world of interaction design, we usually reserve the term for ways of representing interactivity—not just the form but also behavior. For the purposes of this article, therefore, I'm going to focus on things that both look (at least somewhat) like the thing being designed and simulate a response to human actions (clicks, taps, selection, and navigation), even if the simulations are crude or fairly limited (see Figure 1).
For clarity's sake, it's probably worth mentioning that the term also implies a certain amount of disposability. Prototypes are meant to be a cost-effective way of experimenting with ideas. They are generally considered part of the pre-planning phase, rather than part of the construction or manufacturing process that results in the final product—although obviously the discoveries made during the process of prototyping should ultimately both inform and shape the construction process." (Continued via Adobe, Dave Cronin Cooper) [Usability Resources]