Prototype - As a Design Guideline

"A picture can replace a thousand words; a prototype can save you lots of meetings and possibly avoid a project failure."

A prototype is a dynamic view of the system, while a requirements documents and design documents create a static view. It is the same with blueprints; they are a static model. A small-scale model is a dynamic view. Using a dynamic view, you can see things in action; you can add another dimension to the design phase: the time dimension.

The most important benefit of using prototypes is that it helps promote communication with the client, project managers and other developers.

Prototypes help in tracking the requirements back and forth. They ensure that you implement what is needed, no more and no less.